Puregym will open 10 new branches when lockdown restrictions are eased on Monday.
The budget gym operator said the new venues – which were long-term lease commitments made before the pandemic – reflected its commitment to UK expansion.
It said there is “strong and growing demand” for people to maintain and improve their health and wellbeing.
The new gym locations will include Twickenham, Aldershot, Bournemouth, Chelmsford, Crayford, Evesham, Gloucester, Maidstone, Plymouth and Swindon.
Puregym will open its 230 existing sites on Monday following 14 weeks of closure due to the Covid crisis.
Safety protocols will be in place, including social distancing, clean training environments and controlled access and numbers in the gym.
Rebecca Passmore, UK managing director of Puregym, said: “We are re-opening with 10 brand new gyms, our biggest ever weekly expansion, at locations across the country.
“We know there is huge appetite to return to the gym both amongst our existing members and the broader population as people want to resume active lifestyles to manage their physical and mental wellbeing.
“Gyms are great additions to the high street and retail parks and we look forward to welcoming new members and opening more sites as the year progresses.”