The Irishman has been a revelation for the Toffees this season, scoring six goals from right back, including a last minute winner against Cardiff City last weekend.
His form has attracted interest from Premier League giants, but Martinez insists he is crucial to his future plans and wants to reward him for his progress this season.
“We won’t offer encouragement to any club over Seamus. He is on a long-term contract and we want to ensure we grow together and we need players like Seamus,” Martinez said.
“Yes, it is the intention to offer him a new contract. We are already thinking about Seamus, Ross (Barkley) and John Stones. We want to reward them, even James McCarthy.
“That is something we will look at this summer. They are players with long-term contracts. It is not a decision just to keep them at the club; it just highlights the next step of their development and rewards them for their performances.
“Seamus has got a long-term contract. James and Ross are the same. But we want to reward them.”