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, 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 Games in Athens.
