Gilmore, 37, stepped away from competition at the end of 2024, having competed at surfing's Olympic Games debut in Tokyo in 2021 and having won the last of her record-breaking eight titles in 2022.
"The last few years, I've enjoyed time off to do some exploration and other things, but I'm looking forward to heading back to the (championship tour) in 2026, and seeing how I compete against the young talent," said Gilmore, who was granted a season wildcard.
The news will be a big boost for the World Surf League's 2026 Tour, and sets up an intriguing battle between the "old guard" of Moore and Gilmore and a crop of talented youngsters who have lifted the performance bar in recent years.
Gilmore won the first of her record 34 championship tour events as a 17-year-old wildcard in 2005 and won her first world title in 2007 as a tour rookie. Only Kelly Slater, with 11, has more world titles.