The fee is said to be in the region of £20m and the goalkeeper was set to undergo a medical on Saturday.
The deal is now done, with only final formalities needing to be agreed between Martinez and Arsenal before his departure has officially been confirmed.
He has however agreed his contract with Aston Villa and Martinez’s signing is set to be confirmed player imminently after signing a four-year deal.
The writing was effectively on the wall for Martinez after he was left out of the Gunners’ matchday squad against Fulham and Mikel Arteta confirmed the decision was transfer related.
The Gunners ideally wanted to keep Martinez and were prepared to offer him a new contract that will come with a significant pay rise on his £25,000-a-week salary.
Although, they have been aware that the goalkeeper wants regular first-team football in order to commit his long-term future to the club.