The home fans created a hostile atmosphere for their English visitors, with special abuse reserved for former Marseille striker Didier Drogba.
The Blues had yet to register a point on French soil in the Champions League having previously been beaten by a Robert Pires-inspired Marseille five seasons ago and then Monaco last season.
There was cause for concern for Mourinho after seven minutes when Gudjohnsen suffered a whack on the head in an aerial challenge with PSG skipper Jose Pierre-Fanfan and had to be carried off on a stretcher.
He was replaced three minutes later by Kezman.
Chelsea were unhappy Spanish referee Manuel Mejuto Gonzalez had not halted play when Gudjohnsen was lying on the floor, and they were almost punished as Charles-Edouard Coridon broke forward and hooked an effort just wide of Petr Cech’s left post.
A sublime piece of skill by Drogba after 23 minutes when he played a reverse flick and almost let in Tiago, but his control let him down and he bundled the ball wide.
Two minutes later Kezman won a free-kick 30 yards from goal. Lampard shaped to shoot but instead chipped the ball to the far post and Drogba headed into the goalkeeper’s arms.
Chelsea looked confident but were gifted the lead in the 29th minute.
Lampard floated over a corner from the Chelsea left and goalkeeper Lionel Letizi came to claim the ball on the edge of his six-yard box.
However, he amazingly missed the ball completely and skipper John Terry had the simplest of tasks in nodding the ball into an unguarded net.
PSG almost responded two minutes later as Modeste M’Bami drilled in a rising angled drive from the right, but Cech pushed it round his near post with both hands. Chelsea claimed a second goal just as the fourth official held up the board to indicate a minute of stoppage time.
Joe Cole played a brilliant ball into the path of Kezman, who should really have scored but saw the goalkeeper block his low shot with his legs on the edge of the box. Luckily for Chelsea the rebound fell to Drogba who steered it into the empty goal from 18 yards.
One of Mourinho’s changes this season has to have been to show faith in Cole, and that paid off with the youngster setting up the second goal.
He also came close to scoring himself five minutes after the break but saw his 20-yard drive clawed round a post by Letizi.
Kezman’s turn to win a second free-kick was in a dangerous position as he was bundled over just outside the right edge of the box after 75 minutes.
The goalkeeper was rooted to his spot as Drogba stepped up and guided the ball over the wall and into the net to kill off PSG once and for all.
PSG: Letizi, Mendy, Helder, Pierre-Fanfan, Armand, Ogbeche, M’Bami, Coridon, Cana, Rothen, Pauleta.
CHELSEA: Cech, Paulo Ferreira, Gallas, Terry, Bridge, Tiago, Makelele, Cole, Lampard, Gudjohnsen, Drogba.
Referee: Manuel Enrique Mejuto Gonzalez (Spain).