The England forward completed a £16 million move to the Emirates Stadium from Manchester United on Monday night in the final hours of the summer transfer window.
He will wear the jersey last owned by Russian midfielder Andrey Arshavin and also previously worn by the likes of Ray Parlour and Sol Campbell.
Welbeck could make his debut in Arsenal colours in the crunch clash against Manchester City on September 13 following the current international break.
The 23-year-old is believed to have agreed a contract with the Gunners that will run until 2018, with the option of adding a further year.
Arsene Wenger moved to sign Welbeck - beating rivals Tottenham to a deal - after losing Olivier Giroud to a long-term injury and missing out on strikers Loic Remy and Radamel Falcao.