Tottenham twice had to come from a goal behind to keep alive their slim hopes of UEFA Cup qualification.
But the defeat was tough for Albion to take as they had twice taken the lead through Danny Dichio and Neil Clement only to be undone by the heroics of Keane and a strike from golden oldie Teddy Sheringham.
Albion had no answer to Keane who had been taunted all match by the Hawthorns fans having started his career with their arch-rivals Wolves - but he had the last laugh.
Before Dichio struck with a towering header, Keane had threatened to give Tottenham the lead in spectacular fashion.
After a flick-on from Dean Richards, Keane acrobatically fired in an overhead kick that Albion goalkeeper Russell Hoult did well to smother at his far post.
That let-off sparked Albion into life and they made the breakthrough just four minutes later.
Tottenham had been given a sign of what was to come 60 seconds before when Jason Koumas saw his 20-yard free-kick beaten away.
But Koumas was not to be denied and he had a key role in Dichio heading Albion in front after 23 minutes.
The Welsh international whipped in a deep cross from the right-wing that picked out Dichio perfectly.
The former Sunderland marksman was able to escape his marker, Ledley King, on the far post and send a looping header back over Tottenham goalkeeper Kasey Keller and into the far corner of the net.
While Keller was powerless to prevent Dichio scoring, he did perform heroically after 34 minutes to ensure that Tottenham only remained one goal behind.
Derek McInnes saw his 18-yard drive beaten away by the American international after Andy Johnson had headed down a cross from Jason Roberts.
The intervention of Keller proved timely as Tottenham took full advantage of their let-off to equalise in first-half injury time through the lively Keane.
Keane exchanged passes with skipper Sheringham before calmly slotting the ball past Hoult.
Albion regained the initiative on the hour when Clement struck from a 25-yard free-kick with his first touch of the game after Dean Richards had fouled the Albion defender Ronnie Wallwork.
But Albion's bid to record back-to-back Premiership wins for the first time in seven months was dashed only two minutes later.
Sheringham prodded home his 13th goal of the season from close range after Goran Bunjevcevic had headed a chip from Keane against the post.
Albion did at least appear destined to collect a point for their efforts, but man of the match Keane had other ideas.
He latched on to a long clearance from King and fired past Hoult from the edge of the area.