McFadden had a part to play in goals for Iain Vigurs, Lionel Ainsworth and John Sutton before finding the back of the net himself, as the Steelmen bounced back from defeats to Dundee United and St Johnstone.
A Callum Paterson goal when his side were already 3-0 down proved to be scant consolation for a Hearts side who have little hope of avoiding the drop this season.
Motherwell handed a first start to youngster Jack Leitch, while Lee Hollis was back in goal for the first time since early October after recovering from injury.
raig Reid also made his home debut in the clash at Fir Park but ongoing injury problems meant the Steelmen were only able to name six substitutes.
The Jambos named an unchanged side following last week's defeat to Celtic.
It was the visitors who enjoyed the best of the possession in the opening stages without really causing any problems for their hosts.
Motherwell almost opened the scoring when what should have been a tame effort from Ainsworth took a massive deflection off Scott Robinson and forced Jamie MacDonald to be alert.
The Hearts goalkeeper came to the rescue again moments later, this time swatting a McFadden effort to safety.
But Motherwell's persistence paid off when they surged into the lead with 18 minutes on the clock.
Vigurs played a clever one-two with McFadden before drilling low into the net, leaving the keeper with no chance this time.
The home side went in search of another goal but Ainsworth was frustrated as his shot rattled the side-netting, rather than the target.
However, the Steelmen - and Ainsworth - were celebrating again after 37 minutes when he bagged his seventh goal of the season.
McFadden was the provider again with a cross to Ainsworth on the edge of the 18-yard box and he gratefully lashed into the top corner to put Motherwell firmly in the driving seat heading into the break.
Vigurs could have grabbed his second of the day shortly after the restart but a low drive flashed just wide of the target.
At the other end, only the woodwork prevented Hearts from pulling a goal back when Sam Nicholson cut inside from the left and unleashed a ferocious shot that cracked off the crossbar.
Motherwell still looked dangerous and Leitch was denied by the goalkeeper, before Ainsworth's rebound was cleared from a few yards out.
But they extended their lead with a third goal on 65 minutes when Sutton pounced on a loose ball after good work by McFadden and, despite his shot lacking power, the ball trundled over the line.
Hearts did manage to pull a goal back three minutes later when Paterson rose above everyone else in the box to nod home a Kevin McHattie corner and provide the visitors with a glimmer of hope.
But there was no way back when McFadden helped himself to a goal of his own after 74 minutes when he sent a looping header into the back of the net from a Vigurs free-kick.