Walcott, who scored a brace to help 10-man Arsenal hold on for a 3-2 win against Swansea City at the weekend, believes the club's six-game winning streak will put the Bulgarian champions on the back foot in north London.
"I don't think they (Ludogorets) will be looking forward to playing us, that's for sure," said the 27-year-old.
"Especially with the way we're playing and the amount of goals we've scored this season already. I am really looking forward to Wednesday now.
"Everyone will say that this is a fixture we should win and we know we should win it. But we've got to make sure we're ready and we can't be too complacent. That's really important."
Arsenal have been dumped out of the Champions League last 16 in the last six campaigns but Walcott is confident his side have learnt from their mistakes.
"I'll be digging into the players and all the players know that there are no givens in football these days. We've struggled against Olympiacos at home in times gone by," he said.
Walcott's brace against Swansea has given him five League goals for the season, already matching his modest tally in the previous campaign.
"It's my biggest step forward. It's a different sort of energy that I've never really had before," he said.
"I was disappointed not to score three or four (on Saturday) because I should have killed it off. But it's three points and that is all that matters.
"I am happy with the goals, the general play and defensive play as well -- which is probably even more important because I know how well I can go forward, it's just the other bits to do. But now I've been doing that."
(Reporting by Claire Bloomfield; Editing by Ian Ransom)