The All-England Club has been revealed as the buyer of the dress, which sold at auction last July for Â£15,000.
Fiona Butler, 18 at the time, appeared on the Athena poster, which was printed in 1976 and has now sold more than two million copies.
She was wearing a friend's homemade dress and was not paid for modelling.
Her friend, Carol Knotts, made the dress at the age of 12 from a special pattern.
Ms Butler, from Worcestershire, asked if she could borrow it for a photo shoot at the University of Birmingham's tennis courts with her boyfriend at the time, Martin Elliott, who sold the rights to poster company Athena. He died in 2010.
The dress will be put on show at the museum in south-west London.
Ms Knotts, from Gloucestershire, said: "It could have gone to anyone - private collectors, celebrities, who knows?
"I can't quite believe that the dress I used to wear to play tennis in will now be part of the Wimbledon Museum collection. It's incredible."
She said before the auction the garment was "tucked away in a cupboard" that she had thought about offering it to the museum but did not think it would be interested.
The white dress worn in the iconic 1970s Tennis Girl poster will go on display at Wimbledon Lawn Tennis Museum.