Spurs are currently level on points with Newcastle in fourth place in the Premier League despite having only picked up six points in their last six games but Redknapp is adamant that his side will qualify for Europe's elite competition.
"We have to pick ourselves up, we'll finish fourth, I have no doubt about it," he told Sky Sports News.
"We did this the other year, got beat by Portsmouth in the semi-final but came back. We will finish fourth."
Spurs were controversially dumped out of the FA Cup by Chelsea on Sunday and Redknapp says his players need to bounce back from the defeat.
"I've got to find a team among that group who'll have the nerve, the will power and the desire to get that fourth spot now," he added.
"We have to go to QPR next week for a tough game and show we can bounce back. It's important. It's a test of character now. They have to show some character."
Spurs face Queens Park Rangers in the Premier League on Saturday.