The Reds legend says the summer signing has finally adapted to life in English football and now looks the real deal at Anfield.
Firmino cost the Reds nearly £30 million when he joined from German side Hoffenheim last summer, but it took him over four months to score his first goal in English football.
Even after that strike, in the stunning 4-1 win at Manchester City in November, the 24-year-old did not find the net again for nearly another two months.
However, after netting a brace in the 3-3 draw with Arsenal on 13 January, the Brazilian has taken his tally for the season to nine, including scoring in each of his last three matches in all competitions.
Fowler, who is Liverpool's sixth-highest scorer of all time, believes that the forward is now showing that he has the class and quality to be a hit on Merseyside.
The former striker told the Echo: "Firmino has massively improved and looks a real danger whenever he plays now. Earlier in the season I didn’t really know what his best position was.
"But now he looks at his best playing centrally just behind the striker. He looks a different player now. He’s scoring goals, he’s creating goals.
"When he first came there were a lot of questions asked about him but playing in the Premier League is massively different to any other league. The intensity is a lot greater. It took a while for him to adapt but he’s flying now."
Firmino's latest goal came in Liverpool's Europa League last-16 first-leg victory over rivals Manchester United at Old Trafford, and he is expected to be given the nod to continue by Jurgen Klopp for the second leg at Old Trafford on Thursday.
Liverpool are looking to reach the quarter-finals of a European competition for the first time in six years by holding on to a 2-0 lead from last week's match at Anfield.