Defoe's second goal of the season, 11 minutes before half-time, cancelled out Albion's third minute opener from Zoltan Gera who marked his full debut with his first goal for the club.
But after the Hungarian international skipper, a £1.5million summer signing from Ferencvaros, had given Albion the lead it was virtually one-way traffic from Tottenham.
They should really have turned that pressure into their second win of the season, but despite the best efforts of lively England star Defoe, they could not find another way past Albion goalkeeper Russell Hoult.
The point extended both sides' unbeaten starts to the season with Albion having to survive a major examination to secure their third successive draw.
Tottenham, who shocked Newcastle United to win 1-0 at St James' Park last weekend, have now taken five points from their opening three matches.
Gera caught Spurs napping when he raced on a to long headed clearance from Riccardo Scimeca.
He cut into the area and held off the attentions of Noureddine Naybet before beating visiting goalkeeper Paul Robinson with an angled drive from 16 yards.
The Baggies then threatened again after 13 minutes when Geoff Horsfield saw his shot blocked by Ledley King.
Somewhat surprisingly, it was Tottenham who were really sparked into life by the early goal rather than Albion.
The visitors went on to lay siege to the Albion goal and the only real surprise was that it took them until the 34th minute to equalise.
Defoe was a constant menace to the Albion defence with his pace. He had a shot deflected just wide in the 26th minute and when Hoult spilled a long-range drive from Sean Davis three minutes later, Defoe was inches away from converting the rebound.
It was no real surprise when Tottenham did force their way back on to level terms.
Fittingly, Defoe started the move that led to his goal when he raced clear from the halfway line.
He exchanged passes with his strike partner Freddie Kanoute and then drilled home a low shot from 20 yards that Hoult could not hold on to despite getting both hands to the ball.
The shock of having their lead erased did inspire Albion to finish the first-half with a spurt and they thought they had regained the initiative after 38 minutes.
Kanu forced home the ball at the second attempt from close-range after his first effort had hit the post following a cross from Gera. However, the goal was disallowed after Horsfield was ruled to have been offside.
It was a rare moment of worry for Tottenham who could easily have put the game out of reach of Albion in the opening three minutes of the second-half.
First Defoe hit the post from 14 yards after a pass from Davis. Then Albion needed an acrobatic save by Hoult to stay on level terms when he pushed a rising drive from Davis over the bar.
Hoult then frustrated Defoe in the 58th minute with another smart save as Tottenham laid siege to the Albion goal but to no avail.