Sagoe Junior joins Shrewsbury on a season-long loan.
Manager Paul Hurst said: "I'm really pleased to get Charles Sagoe Junior on board because I think we have been lacking options in that wide area.
"He is a player that we have been after for some time - we were interested in him during the January window.
"And this summer he went away on tour with Arsenal so we've had to be patient to get him.
"I think the fact we have been interested in him for some time has helped our case in getting the deal over the line.
"Now we need to get him up to speed because his pre-season has been a little bit different due to him going away with Arsenal.
"He has had some game time but not loads - I think he has acknowledged that himself.
"But we will do all we can to get him up to speed as quickly as possible - whether that is off the bench or whether that is starting games and seeing how long he can go for.
"We are delighted to get him in."