The Manchester City striker opened the scoring in the 19th minute before setting up Roberto Firmino in the second half, to deal an agonising blow to team-mates Sergio Aguero and Nicolas Otamendi.
"I'm speechless,” he said after the game.
“I consider every match to be important, even the ones I don't perform well, because I take lessons from them.
"Tonight I was decided to score, I was very confident from the kick-off.
"I missed a chance, then I managed to score. Firmino was able to spot me well, it gave me confidence.”
Jesus, who was praised by manager Tite after the game, crashed home Firmino’s low cross from six-yards to give Brazil an early lead with his first goal at the tournament.
He later turned provider for the Liverpool forward, showing pace and power in abundance before squaring to give Firmino a simple tap-in 19 minutes from time.
It was a deserved victory for the host nation.
They controlled the game and restricted Argentina to only four shots, though La Albiceleste were still left ruing missed opportunity after Aguero’s header hit the bar and the post kept out a Lionel Messi strike.
Brazil go into Sunday’s final at their iconic Maracana Stadium looking for their first Copa America title since 2007, and Jesus has called for another battling display.
“I'm very happy not only for the goal, but for how the team performed,” he added.
“Last week I've said they would struggle to break our defence.
“We worked hard and battled hard tonight. Unfortunately we couldn't score against Paraguay but we grabbed the goals tonight.
“Everyone should be pleased for the match they played, for the effort. This is Brazil!
“We have to play every match as we've been playing, with the same spirit, that way we will achieve our goals."