The livewire striker thrashed home a volley worthy of winning any game in the 18th minute.
We were worthy of a victory that ended a disappointing sequence of results and although Rovers had their chances, particularly at the start of the second half, only Peter Enckleman in the visiting goal kept the margin of victory down.
Enckleman denied Robbie Keane twice in the first half, then tipped the Irishman's goalbound effort onto the bar in the second half before topping the lot with a fingertip deflection of Defoe's shot after 78 minutes.
With Christian Ziege - outstanding after replacing the injured Mauricio Taricco early - also having a second half effort cleared off the line, it was hard to argue with the result.
We started with Ledley King back in defence for Dean Richards and Rohan Ricketts starting in place of Fredi Kanoute, who moved to the bench.
The first half was our most convincing for a while with Rovers only serioiusly threatening twice - the impressive Jonathan Stead denied by Kasey Keller and then flashing a 30-yarder just wide with the keeper scrambling to his left.
It was busier at the other end. Enckleman did well to turn Keane's shot wide after just five minutes and after Ziege came on for the injured Taricco, Michael Brown headed Stephen Kelly's cross wide.
Then the classic opener. Ledley King spotted Defoe's run, drilled a ball over the top and the striker smashed the ball through Enckleman from the edge of the area.
Rovers hit back within a minute and Keller had to be sharp out of his area to block a Stead half-chance before winning a 50-50 with Andy Cole to the loose ball.
Stead later flashed a shot just wide from 30 yards but it was Enckleman back in action before the whistle, the keeper, in for the injured Brad Friedel, doing well to tip Keane's drive over from 15 yards.
The second half to'd and fro'd with Rovers grabbing the initiative in the opening exchanges. Stead curled arguably the best chance wide from 10 yards after Cole robbed Gardner and the same player was denied one-on-one by Keller a minute later.
With 52 minutes on the clock Jonathan Douglas missed the target with a free header from Tugay's corner but just when we looked on the rack, we hit back.
Ziege's superb crossfield pass picked out Defoe only for the Euro 2004 hopeful to miss his kick.
Kanoute, on for Ricketts, headed powerfully wide and Keane's header was tipped onto the crossbar after a Defoe dash to the byline.
Four minutes later and Ziege robbed Brett Emerton and fed Simon Davies, whose shot deflected just wide. From Keane's deep corner Ziege, six yards out, saw his volley hacked off the line by Michael Gray.
Enckleman saved his best until last - Defoe left Craig Short for dead on the edge of the area only to his his shot, destined for the top corner, tipped aside by the keeper.
MINUTE BY MINUTE GUIDE
1min: First effort at goal, ball not cleared, Douglas sliced volley wide from 20 yards.
5mins: SAVE. Keane one-two with Ricketts, low shot from 22 yards forced scrambling low save from Enckleman to his right.
12mins: INJURY/SUB. Ziege on for Taricco, calf problem.
16mins: Well-worked move on right side, Davies eventually into Kelly, deep cross headed wide by Brown.
18mins: GOAL. Defoe onto ball over the top from King and smashed home on the volley from 18 yards. 1-0.
19mins: SAVE. Keller out quickly as Stead burst through, blocked initial shot with his chest, chased down loose ball, won 50-50 with Cole and picked up injury in process.
28mins: Andresen tried his luck from 30 yards, decent hit but always wide.
36mins: CLOSE. Stead shot out of nothing on the turn from 30 yards had Keller scrambling across goal but ball flashed a yard wide.
40mins: Cole above Kelly to meet Flitcroft cross but angle always against him and headed wide.
43mins: SAVE. Ricketts into Keane, took ball wide of of Short and Johansson, shot from 15 yards tipped over by Enckleman.
44mins: YELLOW. Neill for foul on Keane.
Half-time: Spurs 1, Rovers 0
49mins: CHANCE. Gardner robbed by Cole on edge of box as he looked for a pass, Stead took chance first time and curled wide.
50mins: SAVE. Gardner caught again, allowed Stead to get onto Neill pass, Keller fine save one-on-one to his right.
52mins: MISS. Douglas headed free header over from 10 yards from Tugay's corner.
53mins: CHANCE. Defoe missed kick after Ziege picked him out with superb crossfield pass.
55mins: YELLOW. Andresen for foul on Redknapp.
60mins: SUB. Reid for Neill.
62mins: Ball over the top for Cole, battle with Gardner, Keller out as well but Cole managed to get an overhead kick over Keller but wide.
63mins: SUBS. Emerton for Andresen; Kanoute for Ricketts.
66mins: Bullet header from Kanoute from Keane's cross but flew wide.
70mins: WOODWORK. Superb work from Defoe, skated past Johansson, stood up cross from the byline, Keane header at far post tipped onto crossbar by Enckleman.
74mins: Ziege read Emerton's intentions and made interception, fed Davies whose shot deflected just wide.
75mins: OFF LINE. Ziege lurking at far post from deep Keane corner, volley cleared off line by Gray.
76mins: SUB. Gallagher for Flitcroft.
77mins: Good work from Brown, fed ball into Davies, drive from 20 yards straight at Enckleman.
78mins: SAVE. Defoe left Short for dead, shot from 18 yards superbly tipped aside by Enckleman.
87mins: SUB. Poyet for Redknapp.
Line-ups: Spurs: Keller, Kelly, Taricco (Ziege, 12), Gardner, King, Brown, Redknapp (Poyet, 87), Davies, Ricketts (Kanoute, 63), Keane, Defoe. Subs: Hirschfeld, Doherty.
Blackburn Rovers: Enckleman, Neill (Reid, 60), Flitcroft (Gallagher, 76), Tugay, Cole, Johansson, Stead, Andresen (Emerton, 63), Douglas, Gray, Short. Subs: Yelldell, Babbel.
Referee: Andy D'Urso.
Jermain Defoe's magnificent strike ensured a happy ending at the Lane this season with victory in our penultimate Premiership match.