The England international netted in the 55th minute to help the Gunners to a 2-0 win over Sutton United, where Lucas Perez opened the scoring on 26 minutes.
Walcott says this hasn’t driven him as a player, as he has mostly been playing out wide.
But with a good eye for goal, he calmly finished a good move from Nacho Monreal in his 370th appearance this week.
Speaking to Arsenal Player, Walcott said: “I always wanted to put my all in, hard work, but never really [expected to] be in that category of 100 goals for Arsenal.
“It’s great. I’m lost for words to be fair, because I didn’t really think about it before and it’s just happened. It’ll probably hit me in a few days I’m sure, but I really enjoyed that.
“I’m really proud of that personal achievement of mine. Especially playing out wide, to get that many goals … I don’t want it to stop now. It’s a really good achievement, I’m really happy.
“I couldn’t have done it without the guys as well, past and present, and I can’t thank them enough, all the players I’ve played with up to this point, and this group is brilliant. That’s a special moment for myself personally.”