The campaign debuted over the weekend on ITV during The X Factor.
It shows a man diving into clear blue water with the message, "Thomson is changing to TUI".
The 20-second spot, created by Y&R London, is at the heart of the communications campaign. Variations of the ad will be seen on all long-haul flights on the 787 Dreamliner as well as national TV, bus-sides and out of home sites across the UK, before switching over to a major brand campaign as Thomson finally becomes TUI in the coming weeks.
TUI UK and Ireland, which owns Thomson, announced in late 2015 that the Thomson and First Choice brands would be retired across the UK and switched to TUI in line with the group's international markets.
In December 2016, the company announced that its summer 2017 marketing campaign, "Moments", would be the last under the Thomson brand name.
"The foundations for our rebrand are firmly in place and we are primed ready to become TUI," Jeremy Ellis, marketing director at TUI UK and Ireland, said. "A CRM campaign has been underway since May, engaging with 5m loyal customers and a special issue of our glossy magazine Discover has been sent to 1.5 million people."
Ellis added that customers are already used to seeing the TUI smile logo as it has been a part of Thomson branding for some time.
"TUI has also been visible in our overseas resorts for three years and on our airline livery this summer. People will now notice changes on the high street from this week as our 600+ stores shift from Thomson to TUI," he said.