Carey Price stopped all nine shots he faced in the first half of the game and Matt D'Agostini also scored for Montreal, which won its preseason opener before a sellout Bell Centre crowd of 21,273.
Cammalleri got a kick out of being announced as the game's first star in French.
"I've got to admit since I was a kid I remember hearing, 'La premiere etoile!"' Cammalleri said. "That's something that me and my dad would always tease about, we'd say those words. He's here tonight so I'm sure it was special for him as well."
David Booth and Evgeni Dadonov scored for Florida, which lost for the first time in three preseason games following wins over Ottawa on Wednesday and Thursday.
Jacques Martin, the Panthers' general manager last season, won his debut as Montreal's head coach.
Peter DeBoer, whom Martin hired before last season to take over the head coaching duties in Florida, acknowledged it was a bit odd to look over at the opposing bench and see his former boss.
"I wish him all the luck in the world," DeBoer said. "He gave me my first opportunity to coach in this league and I'll be forever indebted for that. Hopefully they do well, other than against us."
Cammalleri, who signed a 5-year, $30 million free agent deal on July 1, teamed with fellow newcomer Jaroslav Spacek to set up Gomez's goal, which opened the scoring late in the first period.
Gomez, acquired in a June 30 trade with the New York Rangers, brought the crowd to its feet 18:24 in when he pushed Spacek's feed beyond Scott Clemmensen.
Teamed on a line with Gomez and Andrei Kostitsyn, Cammalleri got his second point 8:21 into the second when he took Kostitsyn's pass and put a shot along the ice and under Clemmensen's left pad to make it 2-0.
"It's good to get your feet under you and get going," Cammalleri said. "I think a lot of guys had good games."
D'Agostini made it 3-0 with an unassisted goal at 12:51.
Booth made it 3-1 when he scored 5:27 into the third. Dadonov scored off a scramble at 10:38 to draw Florida within one.
Curtis Sanford took over from Price 10:26 into the second and made 19 saves, 15 in the third when the Panthers held a 17-5 margin in shots.
Clemmensen made 23 saves in two periods. Alexander Salak stopped five shots in the third.