Smolinski scored with 1:46 left in the third period of the injury-filled game to give Ottawa a 4-3 win Friday night.
Senators captain Daniel Alfredsson scored his 25th goal in the first period before leaving with a rib injury in the second after he was hit by Zdeno Chara's slap shot.
"It's one of those things where you just cringe when it's coming at you," said Smolinski, who was hit by a shot as well and had an ice pack on his right ankle following the game. "Alfie's a shorter guy - if it had been anybody else it might have got him in the pants."
Smolinski brought the Corel Centre-record crowd of 20,055 to its feet when he drove in on goalie Garth Snow and beat him for his eighth goal at 18:14.
"As soon as I got it, I was thinking deke all the way," Smolinski said. "Snow's a big goalie and I knew he thought I'd be shooting."
The Senators, who lead the NHL with 57 points in 36 games, won their fourth in a row.
Islanders coach Steve Stirling didn't dress veteran defenseman Brad Lukowich and benched captain Alexei Yashin after Schaefer converted on the power play resulting from Yashin's hooking penalty 3:59 into the third to tie it at 3.
"I was playing almost four lines up until that point but you take a penalty and they score a goal, I can't take a chance that you're going to take another penalty, so I went with the guys who had gotten us to that point, and the other guys had gotten us to that point," Stirling said.
DiPietro was injured early when Smolinski fell on him during a scramble that led to Alfredsson tying the game at 1 at 6:29 of the first.
Islanders trainer Rich Campbell immediately came over to tend to DiPietro, who remained down while the Senators celebrated nearby.
Snow replaced DiPietro, who needed help from his teammates to get to his feet and skate off.
DiPietro walked over near the Senators dressing room to see Smolinski and members his family following the game. He didn't appear to favor either knee and had no further information about the extent of his injury.
"I don't know. I'm going to go see a doctor (Sunday)," said DiPietro, who declined to identify which knee was injured.
Campoli scored his sixth of the season at 18:02 to restore New York's lead and Snow came up with a pad save on Peter Schaefer's penalty shot moments later at 19:21 after the Senators forward was hauled down by Zhitnik on a breakaway.
Campbell again came rushing off the bench 2:07 into the second to attend to Zhitnik, who slid backward into the boards after bumping into Smolinski and was unable to brace for the impact. He injured his tailbone.
Things looked bleak for Ottawa when Jason Blake scored at 7:45 of the second to make it 3-1, moments after Alfredsson left the game when he was hit by Chara's point shot.
Standing in front of Snow, Alfredsson immediately crouched after he was struck on the right side. The right wing, who scored his team-leading 25th goal in the first, stumbled as he struggled to reach Ottawa's bench.
He used his stick to right himself, then quickly discarded it and both his gloves while making his way directly to the dressing room.
"I know it was hard," Smolinski said of the shot. "I was watching the whole time and you never want to see a guy flop around like that."
Senators coach Bryan Murray spoke briefly with Alfredsson after the second period.
"He felt like he couldn't take a deep breath and that comes with a deep bruise," Murray said. "We're hoping that's all. He went to get checked at the hospital and they'll do the X-rays and everything they have to do, but I don't have any other report."
- Yashin was booed every time he handled the puck during the game. The former Ottawa player drew his loudest jeer when his assist on Campoli's goal was announced.
- Lukowich, an alternate captain, had played each of New York's 36 previous games. "I didn't think he's played very well the last few games, plain and simple," Stirling said.
- DiPietro faced six shots.
- Ottawa was awarded a penalty shot for the second game in a row. D Chris Phillips failed to score against Carolina's Cam Ward in a 6-2 win over the Hurricanes on Wednesday.