The 24-year-old has successfully passed at a medical at the Madejski Stadium and will be added to a Royals squad which is aiming for promotion to the Barclays Premier League this season.
And the South Africa international is looking forward to playing for Brian McDermott's side.
Move: Bongani Khumalo (left) has joined Reading on loan
'It's amazing to be here,' Khumalo said. 'It's an unbelievable set-up at Reading - and I just got a great feeling from the club after playing here for Preston at the end of last season.
'I spoke with the manager and he was very ambitious with his plans for the season ahead, so there was only ever one option for me. It just feels right.'
'Bongani is a player we know well,' explained McDermott.
'He played against us for Spurs' reserves and also while on loan at Preston towards the end of last season, before he unfortunately picked up a metatarsal injury.
Aiming high: Brian McDermott (left) will again be gunning for promotion
'I'd like to thank Harry Redknapp at Tottenham for allowing Bongani the opportunity to come out on loan and for giving us the opportunity to have him here.
'We are delighted to have him with us.'
Khumalo first arrived in England at the start of the year, joining Spurs from Supersport United following a successful trial spell at White Hart Lane.
Khumalo was named as a substitute for Harry Redknapp's side on three occasions last season, before impressing in six loan starts with Preston North End towards the end of the 2010/11 campaign.
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