The disappointing 0-0 home draw against Barnet on Saturday left the Cobblers 14th in League Two - seven points off the top seven with 19 games to go.
However, Walker, who rejoined Town in January from Watford on a deal until the end of the season, says his main mission he set himself when deciding to come back to Sixfields is still achievable.
He told the Northampton Chronicle & Echo: "I think we can get into the play-offs and that's one of the main reasons why I came here. I believe, and the rest of the players and the staff believe, that we can do it.
"I'm here until the end of the season and it was a case of me coming here to try to secure a play-off position or maybe even more than that.
"We've got to move on from it (the Barnet game) now and look forward to next Saturday. Wins are what gets you up the table and we're looking to attack now regardless of whether we're at home or away. Our away form hasn't been great but we haven't lost in three games now so hopefully this can be the start of a good little run."
Source: PA
Source: PA