In a deal pushed by Daniel Levy and approved by manager Jose Mourinho, Bale will spend the season back with Spurs with the Spanish giants subsidising a large portion of his wages.
It is the second new arrival from Madrid to N17 this week, as a £25million deal for left-back Sergio Reguilon has also been completed.
It is understood it was during negotiations for Reguilon that Levy asked about Bale, kicking off talks which has resulted in today’s remarkable return.
It is thought that Spurs have an option of extending the loan for a second season, which would see Bale run down the remainder of his contract at Santiago Bernabeu.
The Wales international made over 200 appearances for Spurs between 2007 and 2013, scoring 55 goals with almost half of those coming in his final season.