The former Tottenham striker's first goal for the Hammers set the East Enders on the road to victory before he then played a huge part in Michael Carrick's crucial second strike.
"Les has been a breath of fresh air since he arrived," Glenn Roeder said after seeing his hungry side out-play and out-pass Spurs.
"Today was our best home performance of the season and now we've got to go and build upon it."Boosted by last weekend's vital win at West Brom, Hammers desperately needed to continue their momentum at Upton Park where they had won just one Premiership match all season.
While they welcomed back John Cole, they were without irritated Italian Paolo di Canio who was absent with an apparent stomach upset.
Twice inside the opening ten minutes, injury-hit Spurs had keeper Kasey Keller to thank as he bravely and then brilliantly denied the lively Jermain Defoe.
A head injury sustained by Ferdinand plus bookings for Glenn Johnson, Lee Bowyer and Cole underlined West Ham's stomach for the fight.
Midway through the half, Keller again came to his side's rescue when he pushed Bowyer's vicious shot onto his right-hand post.
But the American keeper would not have been pleased with the way he allowed Ferdinand's powerful low angled 18-yard effort to squirm through his grasp as the Hammers took a 31st minute lead.
In reply Teddy Sheringham headed across goal, but seconds after the interval, Keller was again outdone by Ferdinand as he dropped Carrick's hanging cross under pressure from his former team-mate.
When Dean Richards failed to clear Carrick arrived in the box to drill a 15-yard effort into the unguarded net.
Ian Pearce then saw his far post header clawed away before Ferdinand, job done, retired on the hour.
How Spurs must have wished they still had the fiery veteran striker as Steffen Freund and Sheringham posed more threat to their own fans than David James, with wasteful, wayward long rangers that ballooned high into the crowd.
"Les was smashing for Spurs," said disappointed Glenn Hoddle. "But he made it very clear he wanted to leave us once the transfer window opened."