HILVERSUM, Netherlands, Sept 9, 2012 (AFP) - The 34-year-old Swede - whose wife convinced him to stay on on Friday night despite his son being in intensive care - rattled in a 35 foot putt on the 18th green to record a three-under par round and a four-round total of 14 under par.
Hanson, who also gained a massive morale boost ahead of his second successive Ryder Cup appearance at the end of the month, won by two shots from Pablo Larrazabal of Spain and Scotland's Richie Ramsay.
It was his fifth European Tour title.
Hanson's form will delight Europe's Ryder Cup captain Jose Maria Olazabal, with the clash against the United States at Medinah ourtside Chicago less than three weeks away.
Overnight co-leader Larrazabal finished second after a level-par 70, with Scotland's Richie Ramsey joining him after a three-under round.
Spaniard Larrazabal looked set to claim the title after Hanson, who was one behind at the time, drove into the trees at the 16th.
However Hanson recovered for a par, while on the same hole Larrazabal made a bogey as they went into the final two holes level.
Both parred the penultimate hole before Hanson's lengthy putt on the last placed the pressure firmly on Larrazabal.
He could only manage a par and two birdies in the last two from Ramsey meant they shared second place.
Scotland's Scott Jamieson finished a further two strokes back, while England's Graeme Storm and Spain's Gonzalo Fernandez-Castano, the other players to share top spot overnight, tied for fifth with Henrik Stenson on nine under.
Leading final round scores in the European Tour KLM Open at Hilversum on Sunday (GBR and IRL unless stated, par 70):
266 - Peter Hanson (SWE) 66 66 67 67
268 - Richie Ramsay 71 66 64 67, Pablo Larrazabal (ESP) 69 65 64 70
269 - Scott Jamieson 68 64 66 71
271 - Gonzalo Fdez-Castano (ESP) 67 65 66 73, Graeme Storm 63 66 69 73, Henrik Stenson (SWE) 68 70 64 69
272 - Anders Hansen (DEN) 70 67 68 67, Nicolas Colsaerts (BEL) 70 65 67 70, Gregory Bourdy (FRA) 69 68 69 66, Richard Sterne (RSA) 70 68 66 68
273 - Marc Warren 69 71 66 67, Richard Finch 70 69 70 64, Bernd Wiesberger (AUT) 68 71 65 69, Marcus Fraser (AUS) 69 68 66 70, Bradley Dredge 69 66 70 68
274 - Richard Bland 67 72 67 68, Richard S Johnson (SWE) 70 67 69 68, Tommy Fleetwood 67 73 66 68, Lorenzo Gagli (ITA) 69 67 67 71
275 - Richard Kind (NED) 67 69 71 68, Jamie Donaldson 70 67 70 68, Fabrizio Zanotti (PAR) 65 74 71 65, Martin Kaymer (GER) 65 71 68 71, Matthew Baldwin 71 68 69 67
276 - Felipe Aguilar (CHI) 66 74 66 70, Damien McGrane 70 67 70 69, Thomas Aiken (RSA) 71 69 70 66, Danny Willett 66 69 66 75, Darren Fichardt (RSA) 70 67 68 71, Raphael Jacquelin (FRA) 65 70 71 70