Dunga's men prevailed 1-0 over their South American counterparts in London, with second-half substitute Firmino's 71st-minute goal the difference.
Brazil's clash on Sunday marked their final friendly prior to Dunga naming his squad for the continental competition to be held in Chile - and the coach said he has long been a fan of the Hoffenheim man.
Firmino also impressed in Brazil's 3-1 win over France on Thursday, teeing up Oscar for his team's equaliser.
"There is still a lot of time for the Copa America line-up. I have been analysing Firmino for a very long time," Dunga said of the 23-year-old.
"He has been slowly introduced into the team, and that has helped and he has a big desire to score goals."
Dunga said Firmino - who scored his second international goal in just his fourth cap - would be able to find a bigger club if he continued his exploits with the national team.
"He can play for any club and being on the Brazil team, that comes a lot easier," the coach said.
After taking the reins following Brazil's catastrophic finish to their hosting of the World Cup, Dunga was tasked with rebuilding the country's football reputation - which he has started to do with aplomb.
Brazil have conceded only two goals in eight friendlies since - all of which they have won - and Dunga hailed his players for turning their fortunes in a short space of time.
"I am very happy with the players and their reaction and how they are dealing with things after the World Cup," Dunga said.
"They are working very hard, they know the responsibility of playing for Brazil and they are determined to change what happened in the past."
Chile coach Jorge Sampaoli said he was pleased with his side in defeat, and said he was setting about experimenting with personnel - as he looks to pick the hosts' Copa America squad.
"The plan was to play as many different players as possible," Sampaoli said.
"We had a plan for Iran [Chile lost 2-0] and a plan for Brazil, and I would say that the plan for Brazil turned out slightly better.
"The overall performance today was good, aside from the result and I'm happy with the players."
