Powell made 134 in the first innings of the just concluded Test between the West Indies and New Zealand in Antigua.
Gayle, who also scored a century and shared an opening stand of 254 with Powell, described his innings as patient and responsible.
"You have to give him a lot of credit. He was patient and he selected the right balls to hit," said Gayle, who returned to Test cricket after an 18-month break which came as a result of a dispute with the West Indies Cricket Board (WICB).
"There were times when he had a bit of difficulty scoring, but he was able to hang in there and helped to rotate the strike. I am very happy for him."
Powell's century as well as a knock of 30 in the second innings earned him a jump of 27 places on the ICC test rankings.
The Leeward Island cricketer now sits in 65th position, according to the new figures released Monday.
"I didn't have to give him (Powell) a lot of advice. I just told him to play his natural game and stick to the basics. He knows what he's about and he was able to handle the situations quite well," said Gayle.
"He's got a good head on his shoulders and I was happy to see him get his first Test hundred."
Gayle, playing his first Test since April 2011, re-entered the ICC Test rankings in 21st position following his knocks of 150 and 64 not out.
"I was motivated to do something special and as a team we were motivated to get the better of New Zealand," said Gayle who scored his 14th Test hundred.
"After coming off the good performances in the One-Day Series and the T20s, we wanted to make sure that we did not surrender the initiative."
The 32-year-old left-hander has become the first West Indies batsman to score 1,000 Test runs against the Black Caps.
"I am happy to be here playing Test cricket for the West Indies," said Gayle