The winger scored his side's goal and created four more chances for the team, and Nolan acknowledged that his presence changed the match.
However, the 31-year-old midfielder believes that his side put in a good performance and attributed their improved form to a number of players returning from injury.
"I thought we dealt with them quite well, Adam Johnson made a fantastic impact when he came on but we dealt with him well," Nolan told Sky Sports News.
"It was a massive game for Sunderland, probably bigger for them than it was for us and we knew if we won we would go 12 points ahead of them. Tonight was all about us putting space between us and the bottom.
"We've had a massive injury list and we've dug in and with the camaraderie and what we've built up at the club we always knew we would start picking up points when we got some bodies back."
The win leaves West Ham 11th in the Premier League table, 11 points clear of the bottom three with six games to play.