Newells, which has 11 shops in Devon and Cornwall, becomes a member of the consortium, owned by The Travel Network Group, with immediate effect.
The agency, which is owned by Roger and Helen Hawke, has been running since 1962 and employs 60 staff.
Roger Newell said: “The level of marketing and systems support available to us will take the pressure off our internal team and the passion and commitment that was demonstrated by the management team was impressive.”
Newells’ decision to join Worldchoice is a further boost to TTNG after it signed up Barrhead Travel and Cruise 118 as members in recent months.
TTNG’s chief executive Gary Lewis said: “We are delighted that Roger and Helen are bringing their business over to Worldchoice.
“They operate a highly respected business across Devon and Cornwall and we believe we can add significant value to them in all areas of support we offer, but specifically with our marketing support and technology capabilities.”