David Moyes finally accepted Tottenham's increased offer of £3million for the 28-year-old, and the South Africa player hopes to begin his four-and-a-half year contract with a start for Spurs at Newcastle this Saturday.
Harry's long and impressive career has been built on many inspired signings, such as the talented Rafael van der Vaart in the summer.
As his boys-of-the-moment continue to enjoy a thrilling season, we look back at the bargains the wily boss has clinched in the past.
Paolo Di Canio
After Di Canio scandalously pushed over referee Paul Alcock, then-West Ham boss Redknapp snapped him up for £1.7m in January 1999 - less than half of what Sheffield Wednesday had paid 18 months before.
The Italian striker became a Hammers legend, helping them qualify for the UEFA Cup and scoring the 'goal of the decade' against Wimbledon. He later expressed a desire to one day be West Ham manager.
Genius: West Ham legend Paolo di Canio was snapped up for just £1.7m
Redknapp paid around £2m to bring Kranjcar to Portsmouth in August 2006 and then signed him for the same fee at Tottenham in September 2009.
The Croatia player starred in Portsmouth's 2008 FA Cup triumph and replaced injured Luca Modric in midfield at Spurs. He stood out for his impressive vision and control on both flanks, and was a prolific scorer from distance until injury ended his first season early.
Net buster: Niko Kranjcar chipped in with some handy goals for both Spurs and Pompey
Kitson arrived at troubled West Ham for £2.3million and helped the club survive relegation from a perilous position. He scored in his debut against Tottenham in February 1997, as did fellow new striker John Hartson, and the two went on to form an unbeatable partnership.
After riding high for several years, however, his first-team appearances became rarer and goals became fewer. In 2001, he accused Redknapp of 'freezing him out'.
Saviour: Paul Kitson, together with John Hartson, rescued West Ham from the drop in 1997
Merson moved to Portsmouth in August 2002 at 34 years old, on a free from Aston Villa.
The England midfielder and former Arsenal hero helped Redknapp's side win promotion to the Premier League, scoring 12 times that season.
The manager backed him in his struggles with a gambling addiction that nearly drove him to suicide.
Merson then left for Walsall in the summer, where he became player-manager before retiring to work as a pundit.
One-season wonder: Paul Merson inspired Pompey to promotion in his spell at Fratton Park
Diarra joined Redknapp's Portsmouth from Arsenal for around £5.5million in January 2008, after he had failed to stand out at the rival north London club or at Chelsea before that.
It was the midfielder's big break, as he played every minute of Pompey's remaining FA Cup matches until their eventual win.
After six months, Harry sold the France player for £20m to Real Madrid.
Cup fever: Lassana Diarra (left) celebrates Portsmouth's 2008 FA Cup triumph with Pedro Mendes
Tweet deal for Harry! Pienaar seals move to Spurs after rejecting ChelseaClub-by-club guide to every Premier League transfer deal during January
Explore more:People: John Hartson, David Moyes, Harry Redknapp, Paul Merson, Lassana Diarra, Niko Kranjcar Places: Newcastle, France, Croatia, United Kingdom, South Africa