England forward Walcott has not played since the 2-0 defeat of Tottenham in January.
The 25-year-old was pictured in first-team training with the Gunners ahead of Saturday's match with Hull.
"Good to have you back, @theowalcott!" Arsenal wrote on Twitter.
Walcott's imminent return provides a boost for Arsenal, who lost Mesut Ozil to a knee injury over the international break.
Serge Gnabry, who has been out since March with a knee problem, also trained on Monday.