The forward played a day after a trade to the Anaheim Ducks fell through. Dadonov was traded on Monday, but the NHL voided the trade Wednesday, saying his contract included a limited no-trade clause that had not been complied with.
"I would say it's been a stressful couple of days," Dadonov said. "It's nothing like I could do. I was just waiting on a decision."
Dadonov missed two games waiting for a ruling on the trade, shutout losses to the Minnesota Wild and Winnipeg Jets.
"How he handled the situation, how [the fans] handled the situation, couldn't have been done better," Golden Knights coach Peter DeBoer said. "We needed him out there tonight. He was a big help for us."