"They still need to improve the defensive side of the game, by buying a defensive midfield player. Just by buying Suarez won't make them title winners but it might make them title contenders," he told talkSPORT.
However, Robson also expressed concerns that Suarez's track record for controversy could make him a risky signing.
"He would [make] Arsenal a much better side and title challengers. But there's the other side of him that you don't like the look of," he added.
"He's been banned for biting people and for saying racist comments. Do you want to take a player to your club that's got that sort of history?"
Arsenal have had two bids for Suarez turned down, with Liverpool believed to be holding out for £50m from the Gunners.