He is also the first European to win since 1970.
The 30-year old showed enormous tenacity on the final round as one after the other the major names blew their chances as the wind whipped up and the course became much more difficult. His father Jimmy was present on Father's Day to see his son's historic victory
He joins Padraig Harrington as the first Irishmen in the modern era to win a major championship.
McDowell barely made the tournament proper, scraping in as one of the top 50. However, right from the first round he blazed a trail that despite some setbacks, left him at the eighteenth hole with only a par needed for victory.
He held off the challenge of the biggest names in golf leaving Tiger Woods, Phil Mickleson and Ernie Els in his wake.
McDowell stated that the Pebble Beach golf course reminded him of his native Royal Portrush course in Northern Ireland which he thinks helped him enormously this week.
"Its like an Irish course" he said," a links course and it reminded me of home."
McDowell started the day three shots behind leader Dustin Johnston who collapsed over the front nine when he shot seven over par.
The likable 30-year-old is a huge fan of Manchester United and snooker and fast cars. He is 5 foot 11 inches and weighs 167 pounds.
He is known as a relaxed,, laid back character, who tells it like it is and is not constantly playing the public relations game
His best finish in a major to date was tenth. He has played on the European Ryder Cup team and is a shoo-in for this year's side
Graeme McDowell was born in Portrush, Northern Ireland a seaside town and vacation resort. The local course, Royal Portrush, on the water, is not unlike Pebble Beach, the course he is currently playing.
Like an increasing number of promising junior Irish golfers, McDowell took a golf scholarship at an American university.
He attended the University of Alabama at Birmingham from 1998 to 2002. In 2002, he won the Haskins Award for most outstanding collegiate golfer in the United States.
In 2001 he was a member of the Great Britain and Ireland team which retained the Walker Cup at Sea Island in Georgia.
He turned professional in 2002 and won that season's Volvo Scandinavian Masters, which was only his fourth start on the European Tour. He didn't win in his second season, but in 2004 he claimed the Telecom Italia Open and finished sixth on the European Tour Order of Merit.
In 2005, he divided his time between the European and PGA Tours. He was not yet a full member of the PGA Tour, but his top-50 placing in the Official World Golf Rankings ensured that he received invitations to play in many events in the United States.
McDowell managed two top-ten finishes on the PGA Tour including a tie for second place at the Bay Hill Invitational which enabled him to earn enough money to become fully exempt on the PGA Tour in 2006.
He failed, however, to finish in the top-150 in the 2006 PGA Tour money list and decided to return to the European Tour in 2007.
In 2008 he returned to the winners enclosure by winning first the Ballantine's Championship in Korea and then the Barclays Scottish Open. He played in the 2008 Ryder Cup, earning 2.5 points for the European team and finished the season ranked fifth on the Order of Merit.
In June 2010, McDowell won the Celtic Manor Wales Open by three shots.