Barkley made his club debut in 2011 and has not looked back since, going on to score 16 goals for the Merseyside club and earning 19 England caps since first representing his country in 2013.
"(100 Premier League appearances) is a remarkable landmark for someone of his age. I think last year and the season before that, Ross was a young man with enormous potential," Martinez told the club's website (www.evertonfc.com).
"Today, he showed that he is not a young man anymore, he is still young in terms of age but in footballing terms he is someone ready to lead a team. He has been very consistent all season.
"His decision-making has gone to a different level and I don't think he's just a player with potential anymore, he is an important player for us."
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Martinez also said top scorer Romelu Lukaku, who has bagged 19 goals this campaign, is a doubt the trip to Stoke City on Saturday after the Belgian international picked up a back injury in Wednesday's win.
Everton are likely to be without another key player in defender John Stones, who faces a 10-day spell on the sidelines with a hamstring injury, as they look to avenge a 4-3 loss to the Potters earlier this season.
(Reporting by Shravanth Vijayakumar in Bengaluru; Editing by John O'Brien)
