Arsene Wenger's decision to select Alexis Sanchez through the middle has left Giroud playing second fiddle at the Emirates, with the Frenchman largely appearing off the bench in the opening months of the 2016-17 campaign.
Giroud has scored five times this season despite his lack of starts, however, and Walcott has paid tribute to the Frenchman for his contribution to the team.
"Olivier's strengths are fantastic. I know he will be frustrated with the amount of games he has not played but, if you look at his scoring record and how effective he has been when he has been on the pitch - again [on Sunday against Bournemouth], coming off the bench and grabbing an assist," Walcott told reporters.
Giroud, 30, could miss Arsenal's League Cup clash with Southampton on Wednesday night due to a slight hamstring problem.