A spokesperson for GRG confirmed he had left the London restaurant, but would not respond to queries over his replacement.
Jayasekara joined Petrus as senior sous chef in 2015 under Neil Snowball, and went on to win National Chef of the Year 2016.
He previously worked as a senior sous at Raymond Blanc’s Le Manoir aux Quat’Saisons and the Roux family’s The Waterside Inn.
Speaking to BigHospitality in 2015 Jayasekera said his “ultimate goal” was to win a Michelin star, either at GRG or in his own restaurant.
“Ideally I’d like a restaurant of 60 covers, with a small team of chefs that serves delicious, seasonal food,” he said.
“I trained classically and all I want is to cook food to the best of my ability and create a happy place to work.”
Jayasekara is the latest in a series of departures from GRG. Chief executive Stuart Gillies is believed to have left his role earlier this year after filings show his position as a director was terminated in February.
BigHospitality’s sister site MCA reported last week that Simon King, formerly of Danny Meyer’s Union Square Hospitality Group, has stepped down as director of operations at the company.
Managing director Andy Wenlock is believed to have taken over as chief executive of the business, though GRG has refrained from commenting on reports.