Lopez, who turns 42 in two weeks' time, defeated Chile's Yasmani Acosta in the final of the 130kg Greco-Roman final.
With his victory, Lopez broke a tie for four successive individual Olympic golds he shared with Carl Lewis (athletics/long jump), Michael Phelps (swimming/200m medley), Katie Ledecky (swimming/800m freestyle), Al Oerter (athletics/discus), Paul Elvstrom (sailing) and Kaori Icho (wrestling).
A legend of wrestling, Lopez had retired after the 2021 Tokyo Games before returning to the sport to achieve his landmark triumph.
Despite a three-year absence -- and having suffered four herniated discs -- Lopez stunned world champion Amin Mirzazadeh of Iran in the quarter-finals in Paris.
Victory in the final on Tuesday may have been particularly sweet as it came against Cuban-born Acosta, now a naturalised Chilean.
In six Olympic appearances, Lopez now has 22 victories against just one defeat which came in the quarter-finals of the 2004 Athens Games.
"He is not very interested in glory. He does this for the love of his sport, for his pleasure. If God gave him the opportunity to be the greatest in history, why not take advantage of it?" his coach Raul Trujillo told AFP.
Lopez received a standing ovation from the crowd on Tuesday before the legend placed his shoes in the middle of the mat, a tradition for retiring wrestlers.
"We have to make room for the young people who are coming through to ensure continuity," he had said Monday after qualifying for the final.
"Wrestling has been the love of my life, for all of my life."
His record could be equalled in four years' time if Ledecky, 27, decides to keep swimming at the 2028 Los Angeles Olympics.
