The Belgian buried a low shot with 90 minutes on the clock as City snatched a barely-deserved 2-1 win over Europa League winners Sevilla at the Etihad Stadium.
It had looked like being another frustrating night for Pellegrini's men in the competition with only an Adil Rami own goal, cancelling out an earlier Yevhen Konoplyanka strike, saving them from potential defeat.
But, maintaining his superb form since his £54million move to City two months ago, De Bruyne had the final say after breaking clear from a Yaya Toure pass.
The manner of the result bore similarities to the late win Borussia Monchengladbach three weeks ago and lifted City to second in Group D, just a point behind Juventus.
Despite the unconvincing nature of the win, Pellegrini believes his team are getting to grips with the competition.
Pellegrini said: "I think that maybe there is a lot of criticism of this team in Europe but these two last games that we played in Europe reflect that we have the character to try to win.
"We will continue trying to improve our play, but for me, the character, concentration and intensity in Europe has been very important.
"When you win in the last minute it gives you more trust in what you are doing."
De Bruyne, who has now scored five goals in nine City appearances, said: "We tried everything to look for the victory
Thankfully, in the end, we could score."
City did create a number of chances but had to rely on their counter-attacking abilities as Sevilla controlled possession.
The Spaniards were slick and incisive and claimed a deserved lead through the outstanding Konoplyanka, who had earlier hit the post, after 30 minutes.
City levelled six minutes later when Wilfried Bony's shot was deflected in off Rami but Sevilla remained the better side until the hosts' late burst.
City looked vulnerable in defence throughout and Pellegrini's decision not to start with captain Vincent Kompany, who only appeared as an injury-time substitute, was a big talking point.
Despite having recovered from a calf problem, Kompany has been on the bench for the two games since he played for Belgium against Pellegrini's wishes during the recent international break.
But having been introduced to great acclaim late on, the skipper could now be back in the starting line-up come Sunday's derby against Manchester United - although there are no guarantees.
Pellegrini said: "Vincent is just coming back from a long injury that kept him out for a month, and it was probably a risk to give him the responsibility to play in this important game.
"Tomorrow we will start thinking about the derby and we will see the way the players recover."
Source : PA
Source: PA