The Chelsea manager has also warned Bale of the pressure that will be on him to justify his transfer tag if, as has been speculated, Madrid end up paying a world-record fee to prise him away from Tottenham.
Mourinho, who left Madrid this summer after three years in charge before returning to Stamford Bridge, told ESPN of his hopes to sign Bale last season, saying: "I asked the club to buy him last season but it was not possible.
"It looks like it is happening this season so I am happy for them because they get a fantastic player but, of course, the numbers are huge numbers and the kid has to go now and there's pressure to prove that he's worth that investment."
Mourinho believes Bale would have fitted in well in his Madrid side and expects his successor, Carlo Ancelotti, to make the most of the Welshman's talents as well if he moves to Spain.
"I think he's a fantastic player and the way my Real Madrid was playing, I think it was an easy player to fill a space and to get into that tactical dynamic," the Portuguese added.
"I don't know what Carlo is thinking now but Carlo is an experienced coach and for sure will get the best out of him."
Source: PA
Source: PA