Brian Campbell added two assists as the Panthers won in Kevin Dineen's first game as an NHL head coach. Theodore's shutout was the 31st of his career.
"For me, we have a new feel, a new season," Dineen said. "I liked the way they played tonight."
Earlier in the day, he had attempted to downplay the significance of coaching his first game in the NHL.
Following the win, though, it was evident what the night and the win meant to him.
"(The win) will be more focused on my dad and my family back home," Dineen said.
He said that he had a brother and a nephew in attendance.
"It's exciting. It's exciting as a family," Dineen added. "There (are) a lot of sacrifices and transitions in this hockey business and they enjoy the win as much (as the coaches and players do)."
Weiss opened the scoring with a tap-in of Campbell's shot at 16:37 of the first period. Campbell fired a wrister from the slot at Al Montoya that the New York goaltender could not control.
Weiss spun off a Mark Streit check a moment before he tapped home Florida's first goal of the season.
"Good job by (Tomas Fleischmann) driving the seam and (Campbell) creeping in from the point and got a good shot. It was just sitting on the goal line and I tapped it in," Weiss said.
"I was just going to the net. (Campbell) took the shot and it squeezed by the goalie. It was just sitting there in the crease. It doesn't get much easier than that."
Garrison increased the lead to 2-0 with a power-play goal at 19:45. Campbell sent a pass to Garrison at the point that was one-timed past Montoya.
In addition to his two-point night, Campbell played 30:04 and was plus-1. He was credited with two shots on goal, a hit and three blocked shots.
Campbell was acquired by Florida GM Dale Tallon in a trade with Chicago.
"It's nice. I was telling (Kris Versteeg) on the bench it's a pleasure playing with him," Weiss said.
"When he gets a puck in the neutral zone, you can take your time coming back. He's going to find you with speed. It makes the game a lot easier for the forwards."
The Islanders did not have an easy time as Florida was able to successfully clog the neutral zone and the center of the ice in the offensive zone.
New York's team speed was often neutralized. When the Islanders were able to gain entry into the offensive zone, they were forced into taking harmless shots that Theodore stopped.
"Everybody came through tonight," Theodore said. "They were clearing the rebounds (and) I was seeing the puck. We really worked well as a unit. They were letting me see the puck. We were all on the same page."
Montoya got the start in net for the Islanders and finished with 27 saves for New York.
Dineen had spent the past six years as the head coach of the American Hockey League's Portland Pirates. ... Scottie Upshall was assessed a game misconduct at 19:24 of the first period. ... Mike Mottau committed three minor penalties. Florida was 1 for 5 on the power play. The Islanders were for 0 for 3.