Martinez believes they have developed an understanding and have 'good chemistry
Pienaar marked his long-awaited comeback after seven weeks on the sidelines by netting the winner in the 2-1 home win over Hull City on Saturday.
The 31-year-old South African midfielder scored with his first touch after emerging as a 56th-minute substitute for Leon Osman.
He was soon working in tandem with in-form Baines, a partnership which has proven a bedrock for Everton during recent seasons.
And Goodison manager Martinez is delighted the duo can reprise such an effective combination as his team aim to build on their impressive start to the campaign.
“You get special partnerships in football,” said the Spaniard.
“Leighton and Stevie have developed that over the years so it is important.
“They can also link up with other players.
“Look at the stats. Last season they were most probably the most successful partnership in the league and you need that at full flow. It’s good to have them playing together.
“Leighton and Steven have as good a chemistry as you’re going to find in football.
“I can imagine when Stevie is on the pitch, Leighton knows when to go and that extra second make all the difference to defences. Stevie gives us that freedom.”
Martinez added: “We have partnerships through the team. The central defenders understand so the midfielders.
“If you are a full-back and you have a good understanding you know when and when not to go because you know what he is going to do.
“When you play with other players trying to develop a partnership it can bring doubts.”
Pienaar was a surprise inclusion on the bench with Martinez having initially declared the game was too soon for the South African after recovering from a hamstring problem.
“It was always the plan that Steven couldn’t play any longer than half-an-hour,” said the Everton manager.
“I was looking at the clock thinking how quickly we could get up to 60 minutes. “He got back into the tempo so quickly and his quality is a big asset to the side.
“That is why you need 22 good players because everyone needs to help the team.
“It is about the attitude of the players when they come on and I have been pleased with the subs. They are full-hearted and have knowledge when they come on.”
Saturday’s man-of-the-match James McCarthy, meanwhile, believes his game is improving by playing alongside Gareth Barry in central midfield.
The duo are likely to become a regular feature with Darron Gibson sidelined for much of the campaign after rupturing his anterior cruciate ligament.
Barry has a 100% Premier League record since moving to Everton FC last month, and McCarthy said: “He’s different class. It’s a joy to work with him on a daily basis. You see how much he means to the team.
“I’m gutted for Gibbo because it’s one of those freak injuries that you never want to see happen to anyone.
“The main thing now is that I keep working hard and try to get in the team as much as I can. It’s not about Darron getting injured and me going in there.
“I’m gutted for him and we have to keep his spirits up so he can bounce back as soon as he can.”