His first European Tour win was the 2005 Open de España at San Roque Club, Sotogrande, Spain.

On 27 March 2012, Hanson accepted an invitation to join the PGA Tour for the remainder of 2012 with Special Temporary Membership status.

[5] Hanson recorded his best finish at a major championship in April 2012, at the Masters Tournament at Augusta National Golf Club.

His final round, playing in the last group with Phil Mickelson, started badly with two bogeys in the opening three holes and he never recovered.

[6] On 9 September 2012, Hanson won for the fifth time on the European Tour, taking victory at the KLM Open in The Netherlands.

[8] Making his second Ryder Cup appearance in 2012, Hanson played on the victorious European team against the United States at Medinah Country Club outside Chicago, Illinois, in September.

The month after, on 28 October 2012, Hanson received the biggest prize check of his career, €888,560, when he won the BMW Masters at Lake Malaren Golf Club, Shanghai, China, out-dueling world number one Rory McIlroy, when they played together in the last group of the last round.

Hanson moved to Lake Nona, Orlando, Florida, to play on the PGA Tour in 2013,[9] but after being forced to withdraw before the last round of the 2013 Northern Trust Open in March, due to pain in his back and immediately being driven to a hospital in Los Angeles, the rest of his career has been continuously interrupted by a disc herniation injury.