The French giants scored four tries while fly half Jean-Baptiste Elissalde kicked 18 points to keep the French flag flying in the last four of Europe.
Jason Spice and Ben Blair both crossed for the Blues but they did not have the fire power to maintain their hopes of reaching the final in Cardiff next month.
Toulouse got off to the perfect start when Maxime Medard ran onto Maleli Kunavore's kick for the opening try inside a minute. Kunavore blocked Tom Shanklin's kick as the Blues ran their first possession and the Fijian centre scooped up the ball and hacked ahead for wing Medard to score with ease.
Elissalde stroked over the conversion with ease and added a long range penalty from close to the half-way line four minutes later to open a ten-point deficit that Blair failed to reduce when he pulled his first shot at goal wide.
However, the vistitors were back in the game after 17 minutes when Spice squeezed over for the Blues' first score after Tom James beat two defenders to put Shanklin within touching distance of the try line. Elissalde's tackle was enough to stop Shanklin, but scrum half Spice picked up and dived over from close range.
Blair converted the try as well as a second penalty, either side of Elissalde's successful effort, to cut the lead to 13-10 after Cedric Heymans was shown the yellow card. The Toulouse fullback deliberately infringed at a ruck after his blunder with a quickly taken line-out almost put Jamie Roberts under the posts.
Elissalde made sure Toulouse emerged unscathed from the reduction to 14 men with a snap drop goal moments later before opposite number Spice followed Heymans into the sin bin for a similar offence.
The scrum half dived in after his blocked clearance, by Patricio Albacete, almost put Yannick Nyanga over on 31 minutes. However, Elissalde missed the penalty from out wide on the right-hand touchline and Dai Flanagan scraped the post with a speculative drop goal to leave Toulouse 16-10 ahead at half-time.
Before kick-off, Toulouse wing Vincent Clerc was presented with an ERC award for becoming only the second player in Heineken Cup history to score more than 25 tries but he was denied stretching that record in the 57th minute when the ball struck the corner flag before he touched down.
Yet the pin-point accuracy of his boot set up the second French try as the growing pressure finally told. Elissalde caught Cardiff when he switched the direction of attack from left to right, Heymans added the speed before delivering the scoring pass to Kunavore on 62 minutes.
Cardiff Blues' never-say-day attitude paid dividends when Jamie Robinson stepped off the bench and through the Toulouse defence for Blair to score as the Blues threatened to challenge their hosts all the way.
But Toulouse possessed a gear in their motor that the Blues could not respond to as the weight of possession took its toll with two tries in the final nine minutes. Clerc finally got his 27th Heineken Cup try with one of the easiest finishes in his career. Lock Albacete galloped up field and Toulouse had men queuing to finish.
Replacement Jean Bouilhou then followed from close range, three minutes from time, following Yannick Jauzion's delivery and though Valentin Courrent missed the conversion, Heymans's drop-goal broke the 40-point mark with the last kick of the game.