The Bianconeri had already qualified for the Round of 16, but needed to win 3-0 or by two clear goals other than 2-0 to top the group.
They achieved it with a pair of Cristiano Ronaldo penalties and a Weston McKennie volley.
“Coming to Barcelona, keeping a clean sheet and scoring three goals, that's definitely an achievement," Bonucci told Sky Sport Italia.
“The group is growing. As I said before, we needed to show heart, what we had in the second half against Torino.
“We wanted to do this for the Champions League, but also for us, to create the self-belief within us that we can achieve great things.
“We wanted this so much. We'd already come here and got a good result in the past, but this one was even more beautiful. When you play with this determination and desire to sacrifice yourself, and can count on an infallible hitman like Cristiano, you can do anything.
“It was a great team performance. Now we have to regain our focus, because we have to play like this in Serie A as well. The truth is we've got to take the same approach in Serie A, because it brings victories.
“Wins are not to be taken for granted, you have to work for them, to fight for them. We know the squad has values, the next step is calling on them in every single game."