Ronaldo came off the bench to fire the winner in the first half at Goodison Park, a strike that was his 700th club goal of an incredible career, 20 years and two days on from his first.
It was Ronaldo's first league goal of a season where his game time has been restricted under Ten Hag, and the manager felt it would give him a lift ahead of some crucial matches to come.
"That is really impressive when you score 700 goals, it is a huge performance," Ten Hag said. "I am really happy for him, and congratulations to him.
"He had to wait for it but I am sure more goals will come.
"Every player needs the goals. I have worked with goalscorers, they need goals every season to have that feeling. Once they have some goals, they have the flow. Games go easier. That will happen with him as well."
The victory, United's fifth in their last six league games, took them fifth in the standings, and Ten Hag was pleased with the way his team had responded to their 6-3 drubbing by local rivals Manchester City last week.
"Criticism is normal after a defeat in a big game, a derby, but you have to deal with that and learn the lessons and that is what we did," he said.
"We responded well on Thursday (in the Europa League) and today. We dealt with a setback when 1-0 down and we stuck to the plan, remained composed and did our work. We have to keep the process going."
Everton boss Frank Lampard, Chelsea's record goalscorer, also had praise for Ronaldo on his landmark evening on Merseyside.
"He is one of the greatest players to have graced the game," Lampard said. "To look as physically good as he does now and keep scoring goals, making the abnormal numbers become normal, is incredible.
"I wanted him to score in the Europa League in midweek when I saw he was on 699 goals but sometimes these things happen in football."
