Leicester captain Vardy pounced after just 98 seconds in Van Nistelrooy’s first game in charge, before Bilal El Khannouss and Patson Daka struck to seal victory.
Vardy has now scored the first Premier League goal under six Leicester City managers in the top flight.
It was also Vardy who broke Van Nistelrooy’s record for scoring in consecutive Premier League games when he achieved 11 in a row for Leicester back in 2015.
Van Nistelrooy joked about it on Monday, and he said he told Vardy they had a “big issue” to get out of the way before they could start working together.
“We’ve had one full day together. You could see some stuff worked and some was rusty. We’ve got more time for the manager to get his things across,” Vardy told Amazon Prime after Tuesday’s win.
Leicester defender Conor Coady added: “The lads put in a great shift. We can play better. It was all about winning, it was one for the manager.
“The weekend was a dark place but you have to dig deep. We’ve got a long way to go but it’s a great start.”
‘Good signs for Leicester’
West Ham had 31 shots in this match, their highest tally on record since 2005-06.
The last time an away team had more shots and lost was Chelsea against Birmingham in 2010.
Niclas Fullkrug nodded home a consolation for the visitors, but Danny Ings hit the post with a header, Jarrod Bowen spurned several chances, while Coady cleared off the line from Crysencio Summerville.
“The result is what matters, but I have also seen the game and West Ham were dominant,” Van Nistelrooy told Match of the Day.
“I think our fighting spirit got us through the game and we were effective in scoring. A great night.”
Former England goalkeeper Paul Robinson told BBC Radio 5 Live: “What a result this is for Ruud van Nistelrooy. We were talking about a Leicester team devoid of confidence and ideas before the game, but he’s got a performance out of that group tonight.
“But there’s something there for Van Nistelrooy to work on and what he’s seen tonight would have given him a lot of delight.
“He’s made some big changes. His in-game substitutions and management looks good. It’s good signs for Leicester.”
