Dimitrov was born in Haskovo, Bulgaria to Dimitar, a tennis coach, and mother Maria, a sports teacher and former volleyball player, in 1991. He first held a tennis racket, given to him by his mother, at the age of three, and when he was five he began to play daily. In his early years his father served as his coach, but after the young Bulgarian proved his talent in the tournaments for juniors, he made it clear that he would have to develop in other conditions. At the age of 16, Dimitrov turned professional.

He claimed his first major junior cup, the U14 European title, at the age of 14. In 2006, he won the Orange Bowl U16 boys singles and was later named the Eddie Herr International 2007 Rising Star.

In 2007, Dimitrov joined the academy “Sanchez-Casal”, where he was further trained under the leadership of Emilio Sánchez and Pato Álvarez. A year later, Dimitrov moved to Paris, France, where he joined Patrick Mouratoglou’s Tennis Academy and spent the next four seasons there.

In 2007, Dimitrov was the finalist at the Orange Bowl U18 boys singles losing to Ričardas Berankis of Lithuania. With Vasek Pospisil, he reached the US Open doubles final falling to Jonathan Eysseric and Jérôme Inzerillo.

In 2008, Dimitrov began frequent participation in men’s events. His first title came on clay at a futures tournament in Barcelona. His first ATP level match was at the Ordina Open where he lost to Igor Andreev in straight sets. After his junior US Open title he won back to back futures tournaments in Madrid on hard court and rose 300 places to career high ranking of 477. The achievement attracted enough attention to earn him a wildcard into the Mutua Madrileña Madrid Open qualifying draw where he lost to then No. 64, Florent Serra of France. After being granted another wildcard to the Davidoff Swiss Indoors qualifying draw and defeated No. 122, Jiří Vaněk, in three sets in the first round for his first ATP level win, before losing to Julian Reister.

Dimitrov made his Davis Cup debut for Bulgaria in 2008 as a 16-year-old. Playing in front of a home crowd in Plovdiv, the teenage Dimitrov compiled an undefeated record in both singles and doubles to promote his country into the second division of the Europe/Africa zone. A 17-year-old Dimitrov returned to the Bulgarian Davis Cup team for the first round of the Davis Cup Europe/Africa zone in 2009. Dimitrov was victorious in both his singles rubbers which led to a narrow 3–2 victory over Hungary. He would then take a few breaks from Davis Cup which would result in Bulgaria being relegated back to the lowest division of Davis Cup.

In 2009, he was granted a wildcard to the main draw of the ABN AMRO World Tennis Tournament and scored an upset over then world No. 23, Tomáš Berdych, earning his first ATP main draw win. In the second round he faced world No. 1, Rafael Nadal, and lost in three sets. He was granted a wildcard to the main draw of the Open 13, but lost to world No. 8, Gilles Simon, in the first round, despite serving for the match at ninth game of the third set. He then completed two victories in the Davis Cup against Hungary. He lost to Danai Udomchoke in straight sets in the second round of the SAT Bangkok Open. Four first round exits in Challengers followed. He then reached the quarterfinals after qualifying of two successive Challengers at the Trofeo Paolo Corazzi and Aegon Trophy. He reached the second round of the Aegon Championships after defeating Iván Navarro, but lost in two tiebreaks to Gilles Simon. In Wimbledon where he got a wildcard as the 2008 juniors champion he won the first set of his first-round match against Igor Kunitsyn but then suffered a knee injury. Despite this he attempted to continue but lost the following ten games before he retired.

In June 2010, Dimitrov ended his coaching relationship with Lundgren and was subsequently coached by Australian pro Peter McNamara. Dimitrov and McNamara have ended their coaching relationship at the end of the 2011 season. In 2012, Dimitrov was coached by Patrick Mouratoglou in an attempt to revive his fortunes. On 26 November 2012, Dimitrov left the Patrick Mouratoglou Academy and has joined the Good to Great Tennis Academy in Sweden, which is run by ex-touring pros Magnus Norman, Nicklas Kulti, and Mikael Tillström. On 7 October 2013, Dimitrov announced on his Facebook page that he has hired Roger Rasheed (former coach of Gaël Monfils, Jo-Wilifred Tsonga and Lleyton Hewitt) to be his new coach. On 7 July 2015 Dimitrov announced via Twitter that he would be parting ways with coach Roger Rasheed. On 25 September 2015, Dimitrov announced he had hired Juan Martín del Potro’s former coach Franco Davín, but they parted ways in the first half of 2016.

Dimitrov began dating Maria Sharapova in late 2012. He and Sharapova only confirmed their relationship after the 2013 Madrid Open where the Bulgarian managed his first win against a world No. 1, beating Novak Djokovic. Sharapova and Dimitrov separated in July 2015. At the beginning of 2016, he started discreetly dating American singer Nicole Scherzinger, the lead vocalist of The Pussycat Dolls.

At the 2012 Wimbledon Championships, Dimitrov faced the No. 32 seed, Kevin Anderson in the first round. Dimitrov won in a very close four sets. In the second round, he faced the Cypriot Marcos Baghdatis, where Dimitrov retired due to an injury. His next tournament was Swedish Open. Seeded sixth, he eliminated Rogério Dutra da Silva, Frederico Gil, and third seed Albert Ramos all in straight sets to reach a second ATP semifinal in his career. In the semifinal, he lost to the top seed and eventual champion David Ferrer in straight sets. Dimitrov then competed in the Crédit Agricole Suisse Open Gstaad. He defeated sixth seed Julien Benneteau, Dustin Brown, and Łukasz Kubot. In his third career semifinal, he lost again – this time to Thomaz Bellucci in two tough tiebreaks. On the grass of Wimbledon, Dimitrov represented his country for the first time in the Olympics. In the first round, he defeated Pole Łukasz Kubot again in two tight sets, two weeks after he had beaten him in the Swiss Open quarterfinal. He fell in the second round to the 12th seed, Gilles Simon – his fourth loss against Simon (whom he has never beaten).

Dimitrov would return to Davis Cup competition in 2012 as a top 100 player. The Bulgarians breezed through the round robin tournament held in their home city of Sofia and would once again be promoted to the second division of the Europe/Africa zone. Dimitrov and the Bulgarian Davis Cup team have been unable to advance past the first round since being promoted but have been victorious in their two relegation ties.

Dimitrov represented Bulgaria at his maiden Olympics in London 2012. He competed in the singles competition and advanced past the first round with a straight sets victory over Poland’s Łukasz Kubot. He was then beaten by France’s 12th seed Gilles Simon. Dimitrov made his second Olympic appearance in 2016 Rio where he was beaten in the first round of the singles competition by Croatian Marin Čilić.

Dimitrov is also noted as one of the only players on the tour who can consistently produce trick shots, alongside Gaël Monfils, Dustin Brown, Nick Kyrgios and Roger Federer. He has been known to hit a variety of trick shots and unorthodox shots, such as the Tweener. Sometimes, he does it for entertainment purposes, eventually losing the point. Some of his most famous trick shots include his behind the back drop-shot against Viktor Troicki in the Swiss Indoors 2012 and his successive between-the-leg shots off Jack Sock’s returns in the Stockholm Open 2014. Both shots were considered among the best trick shots ever, with the former considered the shot of the year in 2012.

On 16 December 2013, Dimitrov received the second most votes for the Bulgarian Sportsperson of the Year award, earning 1331 points and finishing just behind wrestler Ivo Angelov.

As of 2013, Dimitrov uses a customized Wilson mid-size 93 square inches prototype racket provided by the Wilson Pro Room Team (as disclosed by pro tour stringers such as the Priority One team members), cosmetic on it is the Pro Staff 95 BLX, it is weighted about 12.oz strung with a 16X19 string pattern. In 2014, he switched to 18X17 string pattern. From 2015 and on, he switched to a 97 square inches head size, similar to Federer’s frame but with a 18X17 pattern. In 2016, he worked with Wilson Pro Room Team to come up with the model now known as the Pro Staff 97S with a thinner beam width of 19.5mm. He is sponsored by Nike wearing the brand apparel and the Nike Zoom Vapor Tour 9 shoes which are also Federer’s shoes of choice.

In June 2014, Dimitrov played at the Queens grass-court event, where he was seeded fourth and had a bye into round two. He beat local No. 168 James Ward in round two, then No. 53 Édouard Roger-Vasselin in the third round, both 2–0 sets. Dimitrov was due to play eighth seed Alexandr Dolgopolov in the quarterfinals, but received a walkover when the Ukrainian retired before the match, citing a thigh injury. Dimitrov then faced first seed, Stan Wawrinka, in the semifinals, and won in straight sets. Dimitrov claimed his first title in a grass court against Feliciano López in three sets, being a set behind and saving a match point. It was the event’s first time in which the final was decided with three tiebreakers, as well as being the longest ever Queens final. Dimitrov also played in the Queens doubles event, with partner world No. 3 Wawrinka (ranked outside the top 150 in the ATP doubles rankings), and in round one they beat local brother wildcard duo of Ken and Neal Skupski in straight sets, but then lost in a tight two-setter to third-seeded Canadian-Serbian veteran duo of Daniel Nestor and Nenad Zimonjić in the second round.

In Basel, Dimitrov beat teenager Alexander Zverev and Vasek Pospisil in first and second rounds, before losing to top-seeded and eventual champion Roger Federer at the quarterfinals for a second year in a row. At the Paris Masters, Dimitrov beat Pablo Cuevas in the second round, but then lost to Andy Murray in the third. This was his last tournament for the year. Dimitrov had an opportunity to qualify for the 2014 ATP World Tour Finals, but he finished 11th. On 22 December 2014, Dimitrov was chosen as the Bulgarian Sportsperson of the Year (earning 1190 points), becoming the first tennis player to win the award.

Ranked world No. 17, Dimitrov had a flying start to the season in Brisbane, reaching the final by defeating world No. 8, Dominic Thiem in the quarterfinals and then No. 3 and defending champion Milos Raonic in the semifinals. In the final he overcame world No. 5, Kei Nishikori, in three sets, winning his first ATP title in nearly three years, his last having been at Queen’s Club in 2014. Dimitrov next moved on to play in the 2017 Australian Open, where he extended his winning streak further, reaching the semifinals. Dimitrov beat 18th seed, Richard Gasquet, in the third round and 11th seed David Goffin in the quarterfinals, before being eliminated by Rafael Nadal in a five-set thriller, which lasted almost five hours, with Dimitrov failing to convert double break points in the fifth set when the score was 4–3 for Dimitrov. The match with Nadal was later cited among the top 3 of best Grand Slam matches in 2017.

At the Australian Open, Dimitrov was seeded tenth. In the first round he overcame Dustin Brown in just 69 minutes, then in the second round he beat Lukáš Lacko in four sets and Marcos Baghdatis in five sets in the third round. Dimitrov lost to sixth seed and eventual runner-up, Andy Murray, in the fourth round in four sets. In February, Dimitrov participated in the Rotterdam Open indoor hard-court event, where he was seeded fifth. In the first round he beat the qualifier Paul-Henri Mathieu 2–1 sets, saving two match points in the second set, but then lost in straight sets to world No. 37, Gilles Müller, in the second round. Dimitrov played in Acapulco next, where he was the defending champion and seeded third. He lost in the second round to Ryan Harrison. On 10 March 2015, Dimitrov played at an annual exhibition tournament in Madison Square Garden against Federer, defeating the Swiss star for the first time.

In July, he participated in the 2015 Davis Cup against Luxembourg, winning all his matches. In August, he started his US Open series campaign in Washington, reaching the third round. Then, he played at the Rogers Cup, losing to Jack Sock in the second round. At the Cincinnati Masters, Dimitrov was eliminated in the third round by the world No. 2, Andy Murray, having missed a match point in the third set. Dimitrov’s weak performance continued at the US Open, where he lost in five sets to Mikhail Kukushkin in the second round.

Dimitrov participated in the 2016 Summer Olympics in the first half of August, but lost in the first round to ninth seed Marin Čilić. The Bulgarian then had a good run in Cincinnati, reaching his third career Masters semifinal. He subsequently beat in straight sets Gilles Simon in the first round and then came back from a set to down to eliminate 16th seed, Feliciano López. In the third round Dimitrov won against second seed Wawrinka and then beat Steve Johnson in the quarterfinals, both in straight sets. In the semifinal he was stopped again by the eventual champion Marin Čilić, after allowing re-breaks twice in the third set. With his performance, the Bulgarian secured the second spot in the 2016 US Open Series standings. In the following week, Dimitrov returned in top 30 of ATP ranking, jumping ten positions to No. 24 spot.

Seeded 22nd, Dimitrov played in the 2016 US Open and reached the fourth round for a second time in his career after beating en route Íñigo Cervantes, Jérémy Chardy and João Sousa before losing in straight sets to second seed, Andy Murray, who allowed Dimitrov only five games in total.

Since June 2016 Dimitrov has been coached by Daniel Vallverdu, a former coach of Andy Murray, during which tenure Murray won 2 Grand Slam Titles. Dimitrov has credited Vallverdu with his upturn in form during the 2017 season and has mentioned several times during interviews and during his thank you speech, following his win of the 2017 ATP Finals, that he is very thankful for his success to his coaching team and particularly Vallverdu. Dimitrov also stated numerous times through the season, that Valverdu changed his mentality towards the game and is the main factor for the way he plays against top ten players. On 7 May 2019, Dimitrov declared that he and Vallverdu had parted ways following a string of unsuccessful tournament participations.

Dimitrov has a solid fast serve, often reaching 210 km/h, (130 mph) up to 220 km/h (137 mph). His first serve has been known to be clutch, often producing aces on important points. Dimitrov employs more top-spin on his second serve, making it slower but more consistent. In 2017 however he had a big problem with double faults as he made 254 of them (around 40 more than 2016), although he made his best season so far.

On June 21, 2020, Dimitrov confirmed on social media that he was infected with COVID-19.