The 12,000-ball haul, worth around €10,000, was lifted from Las Rejas Golf Club in Benidorm, Spain, on the night of June 25th.
A club statement described how staff arriving the following morning found a "completely broken" lock on the metal box in which the balls were kept.
Despite reporting the crime to the police, there was no sign of the missing balls until last Sunday when club members spotted that "there were some men selling balls identical to those stolen" in the nearby municipality of Polop de La Marina, Alicante.
The distinctive yellow balls were marked with the black stamp of the Srixon Volvo brand, according to the Huffington Post.
National Police in Benidorm followed the lead and informed their local counterparts in Polop.
Club staff also headed to the area to find out "who had the balls and was selling them" and to tell the illegal vendors that they would be prosecuted for the theft.
But on Wednesday morning, to their amazement, they found the club's car park and access ramp full of bags of golf balls.
Attached was a note that read: "We apologize. We're sorry for what we did. We're returning the balls to you. Anonymous."
The club noted that not all the 12,000 balls had been returned but that there were "enough".