The 23-year-old forward completed a £16m move to the Gunners on transfer deadline day on Monday, penning a long-term deal at The Emirates.
Welbeck appeared to be making progress at the Red Devils last season after scoring nine goals in 25 Premier League appearances under David Moyes.
And Queens Park Rangers defender Ferdinand is confident that his former United team-mate Welbeck can prove a good signing for the north London side.
Welbeck is a top signing for arsenal. Good business done by them. If he gets that trust to be no.1 striker at AFC he will flourish & explode
— Rio Ferdinand (@rioferdy5) September 2, 2014
Welbeck scored 20 goals in 92 Premier League appearances for the Red Devils.
An Arsenal statement read: “Everyone at Arsenal welcomes Danny to the club and looks forward to his contribution in an Arsenal shirt this season.”
Welbeck, who is currently on international duty with England, could make his debut for the Gunners in the Premier League home match against Manchester City on 13 September.
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