Murphy was born on May 7, 1976 in Smithtown, New York to Irish American parents Maureen and Daniel Murphy, a former assistant Suffolk County district attorney and a veteran of the Vietnam War. He was raised in Patchogue, New York. The name Murphy means “sea warrior” in Irish. He attended Saxton Middle School, where he played youth soccer and pee-wee football, with his father serving as his coach. In high school, he continued playing sports, and took a summer job as a lifeguard at the Brookhaven town beach in Lake Ronkonkoma, New York. He returned to the job every summer throughout his college years.

In 1994, Murphy graduated from Patchogue-Medford High School and left home to attend The Pennsylvania State University (Penn State). He graduated in 1998 with a double major in political science and psychology. Murphy was engaged to his college sweetheart, Heather Duggan, and their wedding scheduled for November 2005.

After graduating from Penn State, Murphy applied and was accepted to several law schools, but decided to attend SEAL mentoring sessions at the United States Merchant Marine Academy. In September 2000, he accepted an appointment to the U.S. Navy’s Officer Candidate School in Pensacola, Florida. On December 13 of that year, he was commissioned as an Ensign in the Navy and began Basic Underwater Demolition/SEAL (BUD/S) training in Coronado, California in January 2001, eventually graduating with Class 236 in November 2001.

Operation Enduring Freedom is the official name used by the United States Government for its War in Afghanistan, together with three smaller military actions under the umbrella of its Global War on Terrorism. The war began on 7 October 2001 with the response of the United States and United Kingdom to the September 11 attacks in New York City and Arlington, Virginia. In early 2005, Murphy was assigned to SEAL Delivery Vehicle Team ONE as officer in charge of Alpha Platoon and deployed to Afghanistan in support of Operation Enduring Freedom.

Upon graduation from BUD/S, he attended the United States Army Airborne School, SEAL Qualification Training and SEAL Delivery Vehicle (SDV) school. Murphy earned his SEAL Trident and checked on board SDV Team ONE (SDVT-1) in Pearl Harbor, Hawaii in July 2002. In October 2002, he deployed with Foxtrot Platoon to Jordan as the liaison officer for Exercise Early Victor. Following his tour with SDVT-1, Murphy was assigned to Special Operations Command Central (SOCCENT) in Florida and deployed to Qatar in support of Operation Iraqi Freedom. After returning from Qatar, he was deployed to Djibouti to assist in the operational planning of future SDV missions.

Murphy was killed on 28 June 2005 after he left his cover position and went to a clearing away from the mountains, exposing himself to a hail of gunfire in order to get a clear signal to contact headquarters for relaying the dire situation and requesting immediate support for his team. He dropped the satellite phone after being shot multiple times but picked the phone back up and finished the call. While being shot, he signed off saying- “Thank You”, then continued fighting from his exposed position until he died from his wounds.

On 4 July 2005, Murphy’s remains were found by a group of American soldiers during a combat search and rescue operation and returned to the United States. Nine days later, on 13 July, Murphy was buried with full military honors at Calverton National Cemetery.

On 7 May 2006, on what would have been his 30th birthday, Murphy’s hometown dedicated the Michael P. Murphy Memorial Park; formerly Lake Ronkonkoma Park. The park contains a black granite wall dedicated to the men lost in Operation Red Wings, with each member’s name inscribed. A black granite stone embedded in the plaza bears the picture of Murphy and his Medal of Honor.

On 11 October 2007 The White House announced Murphy would be presented the Medal of Honor, awarded posthumously, during a ceremony at the White House on 22 October 2007.

On 22 October 2007 the Medal of Honor presentation ceremony was held at the White House. President George W. Bush presented Murphy’s Medal of Honor to his parents.

On 7 May 2007, the Lieutenant Michael P. Murphy United States Post Office was dedicated in Patchogue, New York. The request to rename the historic United States Postal Office located at 170 East Main Street in Patchogue, New York, was submitted as bill H.R. 4101 to the 109th Congress. On 3 January 2006, the 109th Congress approved the request and on 1 August 2006, it was signed by President George W. Bush and became Public Law No: 109–256.

On 7 May 2008, Secretary of the Navy Donald C. Winter announced that DDG-112, the last planned U.S. Navy Arleigh Burke-class destroyer at the time, would be named USS Michael Murphy (DDG-112) in honor of Murphy. On 7 May 2011, on what would have been Murphy’s 35th birthday, USS Michael Murphy was christened by his mother Maureen Murphy, the ship’s sponsor.Murphy was the first SEAL to have a ship named after him.

On 9 July 2009, the newly constructed Combat Training Pool at the Naval Station Newport, Rhode Island was dedicated in honor of Murphy. The pool is an L-shaped, 8-lane pool which holds approximately 347,000 gallons of chlorinated water. The training pool also has a training platform three meters above the water which is used for military training, abandon ship drills, etc.

On 2 November 2010, it was announced the senior gift for the Pennsylvania State University (Murphy’s alma mater) Class of 2011 will be the Lt. Michael P. Murphy/Penn State Veterans Plaza. The plaza will honor all Penn State veterans and Penn State’s only Medal of Honor recipient, Murphy.

Operation Red Wings was a counter-insurgent mission in Kunar province, Afghanistan, involving four members of the United States Navy SEALs. Murphy and two other SEALs, Danny Dietz and Matthew Axelson, were killed in the fighting, in addition to 16 U.S. special operations soldiers, who were killed when their helicopter was shot down while attempting to extract the SEAL Team. Prior to a helicopter being shot down in 2011, it was both the largest loss of life for U.S. forces since the invasion began and the largest loss for the SEALs since the Vietnam War. Marcus Luttrell was the only surviving U.S. sailor from the squad; he was protected by local villagers, who sent an emissary to the closest military base, allowing a rescue team to locate him.

In the 2013 film Lone Survivor, Murphy is portrayed by actor Taylor Kitsch.

In April 2014, Patchogue-Medford High School in Medford, New York, named its campus the “Navy (SEAL) Lt. Michael P. Murphy Campus” after its fallen former pupil.

The memorial was vandalized by a 14-year-old boy in 2018. Murphy’s parents forgave the teen and stated that they did not believe “he understood the significance of what he had done”.