The Portuguese international has been linked with a move to Manchester United in the past.
According to Telegraph, Inter Milan and West Ham been in talks regarding the transfer and an agreement has been reached between the two clubs.
However, Joao Mario has not made up his mind about the move and the player is thought to be weighing up his options.
It is evident that the 24-year-old is not a starter for Luciano Spalletti and the midfielder will have to leave in order to play regularly. However, Inter Milan rate the player highly and they do not want to sell him now. A loan move is the best solution for all parties here.
Inter signed the midfielder for a fee of £39.8m back in the summer of 2016.
The report adds that signing a midfielder is a priority for David Moyes in January. There is no doubt that Joao Mario would be a tremendous addition to West Ham.
The 24-year-old was sensational for Sporting and he was a part of the squad that won the Euro 2016 as well.