The former Manchester United, Everton and England forward hailed an “incredible” achievement by the Albion man after he set a new mark for Prem appearances.
Milner played a central role for his side in a 2-0 win at Brentford as he reached 654 top-flight games.
Earlier this season, he passed 1,000 career appearances for club and country when including under-21 internationals.
Rooney told viewers of BBC TV’s Match Of The Day: “That achievement is incredible, to keep playing.
“He started the same year I did as a 16-year-old and to still be going at 40.
“When you play with him, you get to know him.
“I expected him to go on and play for that long because he is so professional, he does everything right, he works hard.
“And he had a big influence on the game today.
“I thought he was fantastic and he has adapted his game.
“He has played off the left, off the right. He has played at full-back and today he played in a double pivot in midfield and he was all over the pitch.
“I think there is a few years left in him!”
Fellow pundit Micah Richards believes Milner is highly regarded for his work rate but his technical ability as a player might be under-rated.
The former Aston Villa and Manchester City defender said: “Absolutely incredible. He is such a top guy as well, you can’t be anything but happy for him because of how he applied himself in training. Always first in, last out.
“He always gives 100 % and I think, in terms of his ability, it is not rated as high as it should be.
“People say he has got very good work rate and he scored a few goals but the transition to go from Leeds where everyone talked about him, wonder kid.
“Then he went to Newcastle, I played against him.
“I thought that might just be his level at the time, playing on the wing.
“Then he goes to Villa, scores all those goals, gets his big move to Man City, where he is a Premier League winner.
“Then goes to Liverpool after that and obviously now he is at Brighton.
“It is just a perfect career and to do it how he did it, I have got nothing but admiration for him.”