Hansen fired a 7-under 63 Saturday for his second third-round lead in as many weeks, moving two strokes in front of Robert Rock at 10-under-par 200 overall.
Last week, Hansen was beaten by Graeme Storm at the Open de France after shooting a 72 in the final round.
He hasn't won since the 2002 Irish Open.
'Without a win for five years is a long time,' said Hanson, 33.
Rock had a 4-under 66 Saturday to climb from a tie for 10th place overnight into solo second place at 8-under 202. Looking for his first win, the Englishman is enjoying his highest career position after 54 holes.
He is currently 134th on the Order of Merit.
'It is not much fun being at the bottom end of the Order of Merit, so I will just try and ignore that and enjoy the fact I am in contention,' Rock said. 'If I play like I did today, then I won't be too far away.'
Niclas Fasth shot a 70 to lead a group of four players who were tied for third place at 7-under 203. He was joined by Peter Hanson, who made a hole-in-one at the shortened 18th for a 66, as well as Gregory Havret (68) and Peter O'Malley (63).
Hansen birdied each of his last three holes at the K Club -- from putts of 15, 40 and 12 feet -- to shoot a 30 on the back nine, vaulting past a slew of players on his way to the top of the leaderboard.
He is 1-4 in his previous five tries with the 54-hole lead, the only win coming five years ago in Ireland.
'I will take it one step at a time because last week I was sitting here saying the same thing,' said Hansen. 'I have come off a terrible season, but now I am playing good golf and putting myself in contention -- and that's what it is all about.'
Colin Montgomerie (71) sits four strokes off the lead at 6-under 204, one of 18 players who stood within five shots of Hansen heading into the final round.
That group did not include Irishman Padraig Harrington or U.S. Open winner Angel Cabrera, who were both well back.
Surprising second-round leader Pelle Edberg had a disastrous finish Saturday, posting two double-bogeys and a bogey in his last six holes to shoot a 73. On a day when players were going low at a shortened course, that wasn't nearly good enough.
Edberg tumbled into a tie for 14th place at 5-under 205 -- five shots off the lead.