Blake has been at the club since 2005 where he started as a part-time coach, but he is now expected to join Sunderland's Under-21 squad as a performance analyst.
The 27-year-old has been a key member of Carlisle's youth set-up, helping the club with the implementation of the Elite Player Performance plan, which is designed to help nurture home-grown talent.
Blake insists he was not seeking a move away from Brunton Park but could not resist the draw of the Premier League.
He told the News & Star: "I wasn't looking to leave Carlisle but when Sunderland called and offered me the position I was very flattered.
"It's an interesting job at a good club and I decided to give it a go.
"It was a hard decision because, while there has been a lot of bad press around Carlisle, I do feel they are going in the right direction and trying to do things the right way.
"It is sad to leave but sometimes you have to take these chances."