TUI had put Travelopia, comprised of over 50 brands offering specialist luxury, adventure and education holidays, on the block in September as part of a push to sell non-core assets.
It said late on Monday that it would invest proceeds from the sale, which valued Travelopia at 14.4 times Travelopia's 2015/16 operating profit (EBITA), into the transformation of its business, without being more specific.
The sale will result in a non-cash charge of around 133 million euros but will have no impact on TUI's full-year guidance for underlying earnings before interest, tax and amortization (EBITA) to grow by at least 10 percent at constant currencies this year.
TUI said it would provide further details on its guidance when it publishes fiscal first-quarter results on Tuesday.
Citi and Barclays advised TUI on the transaction, with Citi taking the lead.
Reporting by Maria Sheahan; Editing by Georgina Prodhan