The 65-year-old has been out of the game since his surprise sacking by Tottenham on June 14 despite leading them to a fourth-placed finish in the Premier League last season.
But Redknapp has now agreed to return to Bournemouth - where he began his career in management in 1983 - to offer advice and expertise to the League One club.
Redknapp enjoyed a successful time at Bournemouth, helping them escape relegation from the Football League in his first season in charge before producing a shock FA Cup win over holders Manchester United.
The Cherries were crowned Third Division champions in the 1986/87 season but were relegated several years later and Redknapp quit the club in the summer of 1992.
Redknapp will travel with the squad to Saturday's league clash with Yeovil at Huish Park and chairman Eddie Mitchell told the club's official website: "I met Harry for a chat and he offered to come in on a voluntary basis. He still has a passion for the club and for football and he's got too much to offer for us to let him slip through our fingers. It's been in my mind for quite some time to get him involved, and the timing seems to be perfect for us to tap into his knowledge."