The Three Lions head to Russia on the back of an unbeaten qualifying campaign that saw them collect 26 points from a possible 30.
England have a disappointing record at major tournaments, though, most recently being dumped out by Iceland in the first knockout round of Euro 2016 after finishing second to Wales in the group stage.
Walker concedes that "a miracle" is required if his side are to go all the way, and the full-back is eager for supporters to not get carried away.
"I hope we can go as far as we can go, but we need to be realistic," he told talkSPORT. "To win the World Cup is going to be a miracle, but we have got the players to do it. A lot of us play in probably the best league in the world.
"We've got the players to do it, but have we got the experience going further along in competitions? No we haven't. Not in recent years. We need to be realistic. There are a lot of good teams out there and our record in tournaments has not been fantastic.
"We've had a lot of conversations inside the camp - England haven't won a knockout game for God knows how many years, so for us to go there and win a knockout game, that would be a step in the right direction."
England face Tunisia, Panama and Belgium in the group stage of Russia 2018.