Walcott has had a stuttering season due to a catalog of injuries, but is now fully fit.
"Hopefully I'll get a start [against Olympiacos]," he told Arsenal TV Online. "[Then I want to] build on from that and get a consistent run of games, that's really important for me at the moment."
The 20-year-old also says that the game is a good opportunity for some of the Gunners' younger players to make an impression, with Arsène Wenger set to deploy a 'Carling Cup' squad in Greece.
"It's always good to qualify for the Champions League early so you can focus on the Premier League," said Walcott.
"It gives opportunities to players who don't get a chance to play as much in these games and it's a great experience for them all."