The 26-year-old was heavily linked with a sensation move to Arsenal over the summer but ultimately decided to stay and sign a new contract at Real Madrid.
Vinicius is yet to get into top gear this season, however, with just one goal in his six appearances, though he has provided a team-leading three assists.
He was booed by his own fans during Real Madrid’s home 2-1 Champions League win over Inter Milan on Tuesday (September 8).
Despite that, Mourinho is happy with what he’s seeing from the Brazilian forward.
"The best version of him is scoring goals," Mourinho said ahead of Madrid's LaLiga clash with Elche.
"Obviously, assisting is important; working for the team is very important. Commitment, solidarity, and teamwork are very important.
"The day-to-day work is also very important, and he does it very well, but there's another Vinicius.
"There's the Vinicius who arrived in Lisbon last season, and in close matches, especially in the two knockout rounds, he gets one chance, scores a goal, and that's it. He's lacking that top-level performance lately, but I'm happy with him."