After Watford were relegated from the Premier League last season, Capoue was heavily linked with a move during the most recent transfer window.
The French midfielder was attracting strong interest from Valencia, but the Spanish club couldn’t find the funds to sign him and reunite the 32-year-old with his old boss, Javi Gracia.
Capoue ended up staying and, following the closure of the transfer window, he withdrew his request to leave Watford.
The midfielder has since been reintegrated into training and could make his first appearance of the season against Blackburn after missing Friday’s win over Derby with an ankle issue.
“He [Capoue] is the guy who wants to come back, to give his best for the team,” Watford head coach Vladimir Ivic told Watford’s website.
“All of us are satisfied that he is coming back to work with us. It was not because of me that he stayed out the previous one-and-a-half months. It was because of his reasons; to do with injuries and the transfer window.
“I expect he will adapt as fast as possible with the new system and the new conditions of the team.”
Club-record signing Ismaila Sarr is also due to feature against Blackburn after missing the win over Derby on Friday.
That came on the same day Crystal Palace failed with a £25million deadline day move for the forward, but his absence was due to him being exhausted from international duty with Senegal – who put their squad through its paces with a double session after their game with Mauritania was cancelled.
“He stayed out because he was tired from his trip and now he works normal and is available for the game,” said Ivic.
“I discussed with him lots about his ability and he says he’s motivated and wants to be part of us. He’s one of the players who gives his maximum every day to the practice and I am satisfied he is with us now the window is closed.
“He is part of Watford and will show his quality and his potential. He is a fast player, who attacks the space and knows what to do one against one. He can give us different quality than other players.”