The Magpies are two points from safety and face Redknapp's Tottenham at White Hart Lane on Sunday.
"It was a fantastic appointment," Redknapp said on Shearer becoming temporary Newcastle manager.
"They couldn't have picked anyone better than Alan Shearer - he was the one person who could get the place a massive lift like he has.
"He has fantastic knowledge of the game and what he achieved in the game makes him one of the all-time great players. If anyone can pull Newcastle around Alan is the man to do it."
"If you look at Liverpool when they took Kenny Dalglish, what a job he did there," Redknapp said. "He came straight out of playing into managing. When you have that type of knowledge that Alan has got it is not a problem."