London Irish (7) 13
Try: D Armitage Con: Lamb Pens: Lamb, Bowden
Toulon (13) 19
Try: Wulf Con: Wilkinson Pens: Wilkinson 4
Wilkinson was denied an early try by Buckland's tackle
London Irish's stuttering season took a turn for the worse as they suffered their second Heineken Cup defeat.
Two Jonny Wilkinson penalties nudged Toulon into the lead and he then converted Rudi Wolf's try to give the French side a 13-0 advantage.
Delon Armitage's converted try and a Ryan Lamb penalty saw the Exiles cut the lead to three points.
But Wilkinson landed two more penalties before Daniel Bowden's kick earned Irish a losing bonus point.
Despite the consolation of a bonus point London Irish will head to the south of France for next week's return match bottom of Pool Three on five points, while Toulon now have eight points, two behind leaders Munster.
French clubs might still have a reputation as poor travellers but with five Englishmen in their ranks the visitors looked right at home as they tore into the Exiles up front.
Backs Wilkinson and Paul Sackey were joined by battle-scarred veterans Dean Schofield, Joe El Abd and Kris Chesney in the Toulon pack and the latter trio helped lay the platform for Wilkinson to guide Toulon to victory.
The hosts were turned over numerous times at the breakdown and have now lost six games in a row in all competitions.
Exiles fly-half Lamb missed an early penalty from wide on the right before veteran England number 10 Wilkinson dropped the ball over the line as he was hit in a heavy tackle from behind by James Buckland after racing onto Pierre Mignoni's chip.
From the resulting scrum Toulon, who had been penalised in the first engagement of the game, won a penalty themselves as Carl Hayman and his team-mates got the upper hand.
And Wilkinson showed Lamb how to do it as he bisected the posts from a very similar angle to the one from which Lamb had failed.
A couple of minutes later Wilkinson stroked a second penalty over from further out to give the French club a 6-0 lead with an hour to play.
When the Exiles knocked on deep in the Toulon half the visitors countered to score the first try of the game.
Joe van Niekerk, who had already made one 50m break, played the rugby equivalent of a one-two with Gabiriele Lovobalavu, before sending former All Black winger Wulf cruising over under the sticks.
The conversion was a formality for Wilkinson and took the lead out to 13-0, and Toulon then came agonisingly close to the score which would surely have killed off the game, even at such an early stage in the match.
When Lamb missed touch with a penalty for the second time in quick succession Toulon launched a threatening counter attack but Sailosi Tagicakibau intercepted a scoring pass 10m from the line.
Delon Armitage, Seilala Mapusua and Jonathan Joseph combined on the counter before Armitage kicked ahead and won the race to touch down and give the hosts a lifeline.
Lamb converted and if ever there was a 14-point moment in a game that was it.
From facing a 20-0 half-time deficit the Exiles only trailed 13-7, with Wilkinson missing a drop-goal in the dying seconds of the half for Toulon.
Despite the lifeline for London Irish, Toulon were in no mood to let them back into the game, and the visitors continued to look the more dangerous side.
After 50 minutes Sackey was tackled off the ball by Paul Hodgson as he led the race to touch down a kick ahead.
But an overly-ambitious tap penalty from Toulon put the visitors in trouble and when they killed the ball at a ruck after Mapusua had threatened their line, Lamb's penalty cut the gap to three points with more than a quarter of the game to play.
Eight minutes later he was handed the chance to level the scores but his long-range effort drifted left of the posts and Wilkinson landed his third penalty two minutes later to restore Toulon's six-point lead.
London Irish tried to conjure a winning score but Toulon kept them at arm's length and twice came close to scoring a second try.
Geoffroy Messina knocked on with the line at his mercy after he had kicked ahead before Wulf just failed to hold an inside pass a yard from the London Irish line.
They finally made the game safe when Wilkinson landed a fourth penalty with five minutes remaining, and the losing bonus point secured by Bowden's penalty will be little consolation for the hosts.
London Irish boss Tony Booth:
"Jonny Wilkinson didn't look on the decline to me. In a tight game they have a 100% kicker and we don't. That is the nature of it.
"He stopped George Stowers at full bore 10 metres from the line, and [he did the same to] Seilala Mapasua. He is probably like fine wine. He is actually getting better.
"Next week we have got to go there to win. London Irish don't like doing things the easy way. Leinster away last year no-one gave us a chance.
"This is a ready-made opportunity to go and upset the apple cart."
London Irish: D Armitage; Joseph, Seveali'i, Mapusua, Tagicakibau; Lamb, Hodgson, Dermody, Buckland, Rautenbach, Kennedy, Casey, Thorpe, S Armitage, Hala'ufia.
Replacements: Ojo for Tagicakibau (71), Bowden for Lamb (71), Allinson for Hodgson (74), Corbisiero for Dermody (74), Ion for Rautenbach (65), Roche for Casey (72), Stowers for Hala'ufia (54).
Not Used: Blaney.
Toulon: Lapyeyre; Sackey, Messina, Lovobalavu, Wulf; Wilkinson, Mignoni, Taumoepeau, Bruno, Hayman, Schofield, Chesney, Missoup, El Abd, van Niekerk.
Replacements: Loamanu for Messina (77), May for Wilkinson (77), Magnaval for Mignoni (68), Basteres for Taumoepeau (57), Ivaldi for Bruno (57), Merabet for Hayman (74), Suta for Schofield (62), Sourice for El Abd (75).
Ref: N Owens (WRFU).