The Gunners negotiated a deal with Italian side Bologna during the summer transfer window and brought the Japan international defender to north London.
He has been waiting to have a work permit approved to be able to place himself at the disposal of Arsenal boss Mikel Arteta.
Tomiyasu has now received the green light on his work permit and will be aiming to be in Arsenal’s matchday squad to face Norwich.
The 22-year-old is able to operate as a right-back or a centre-back and gives Arteta extra options.
Arsenal have yet to manage a win in the Premier League so far this season and the pressure is mounting on Arteta.
They will still start as strong favourites to see off the Canaries at the Emirates Stadium on Saturday though.
Norwich have also lost their opening three games of the season, but have scored once, while Arsenal have yet to hit the back of the net.