Having beaten Celtic at home already this season, the win completed a memorable double for a Well side who remarkably started the match bottom of the table.
For Rangers, the winter break can’t come quick enough.
With several key personnel still out injured, the Light Blues started again with the 3-4-3 formation that had been so effective in the second half of Sunday’s match with Partick Thistle.
Fernando Ricksen and Claudio Caniggia returned to the starting line-up, with Alex McLeish deeming Russell Latapy and Alan Hutton surplus to requirements at Fir Park.
Caniggia had spoken beforehand of Rangers’ need to stay concentrated for the full 90 minutes but their minds seemed elsewhere as they struggled to gather momentum throughout the match.
Passes went astray and promising moves broke down as the Light Blues failed to put the Motherwell defence under any real sustained pressure.
It was 14 minutes before Francis Dubourdeau in the home goal was called into action when he looked sharp to deny Ricksen after the Dutchman had worked a neat 1-2 with countryman Michael Mols.
Ricksen was making his last appearance before a two-game suspension and was one of Rangers’ more lively players in the opening spell.
The only blot on the former AZ Alkmaar defender’s report card was when he picked up a yellow card for a tussle with McFadden wide on the touchline, with the Well striker also booked.
Much has been said – and written – about the spiky-haired Motherwell front man this season but his value probably plunged a few quid after he wasted a few gilt-edged chances to give his side the lead.
He robbed Bob Malcolm in 13 minutes and hared towards Stefan Klos only to blast the ball wide with the goal at the mercy.
As the opening period petered out, McFadden then slid the ball past the other post when a goal had looked inevitable.
A firm drive from Kevin Muscat and a header by Mols both brought out good saves from Dubourdeau but you suspected that the Frenchman had one eye on the television cameras as he plucked the ball out of the air both times with rather over-dramatic flamboyance.
There was little festive cheer for the visiting support as play recommenced after the break and, after de Boer had shot wide and Muscat had an effort well blocked, Motherwell went a goal ahead.
Steven Hammell launched a free kick into the box where Dirk Lehmann seemed to barge into Lorenzo Amoruso and the Rangers defence froze as if expecting a free kick.
No whistle came from referee Willie Young and McFadden was first to the loose ball and rammed it past Klos.
After Mols was booked for complaining, McLeish brought on Billy Dodds to partner him in attack, with Caniggia returning to the bench.
A spectacular save denied Dodds from netting with a diving header and then Peter Lovenkrands squeezed through but shot wide of the target as Rangers slumped to their first defeat of the season.
MOTHERWELL: Dubourdeau, Corrigan, Hammell, Kinniburgh, Pearson, Partridge, Cowan, Leitch(c), Adams, McFadden, Lehmann.
Subs not used: Woods, Ramsay, Ferguson, MacDonald, Clarkson.
RANGERS: Klos; Malcolm, Muscat, Moore, Amoruso; Ricksen, Ferguson(c), de Boer; Caniggia(Dodds 71), Mols, Lovenkrands.
Subs not used: McGregor, Reid, Nerlinger, McLean.
Man of the Match: Kevin Muscat
Referee: Willie Young