Eden Hazard equalised with a 27th-minute penalty and then hit the woodwork as Chelsea recovered from a nightmare start to the Champions League quarter-final first leg in Paris.
The Blues, playing without a recognised striker after Fernando Torres was left on the bench, went behind in the fourth minute.
John Terry’s weak header dropped to Ezequiel Lavezzi and the Argentine fired home with a classy half-volley from 10 yards out.
Chelsea will be without Ramires for the second leg after the Brazilian was yellow-carded following a foul on Lavezzi.
But their prospects ahead of that return leg improved when Hazard scored from the spot – his 17th goal of the season – after Thiago Silva brought down Oscar.
Having made such a strong start, Paris St-Germain faded and struggled to get strikers Zlatan Ibrahimovic and Edinson Cavani into the game.
And Hazard almost put his side ahead with a stunning left-footed volley against the post after the Belgian had been found by Willian.
Cavani appealed in vain for a penalty following a challenge from Gary Cahill moments before the interval.
Chelsea: Cech; Ivanovic, Cahill, Terry, Azpilicueta; Ramires, Luiz; Willian, Oscar, Hazard; Schurrle.
Subs: Schwarzer, Kalas, Ake, Mikel, Lampard, Torres, Ba.