The 23-year-old moved to North London last summer but had an underwhelming first season in English football, scoring six times in 35 appearances in all competitions for Mauricio Pochettino's side.
Spurs informed the Dutchman that he was free to leave the club this summer and he almost completed a switch to Brighton & Hove Albion, only to turn down the deal in the final minutes of transfer deadline day.
With it looking likely that Janssen will now be frozen out of Pochettino's first-team plans, the forward has reportedly agreed to spend the season with Turkish Super Lig side Fenerbahce.
In a statement published on their website this morning, the club said: "Our club in principle has agreed with the player himself and his club on the leasing of Tottenham Hotspur and Dutch national team striker Vincent Janssen.
"The 23-year-old striker will arrive at Istanbul Ataturk Airport at 12:30 today and negotiations will continue in Istanbul."
While the Premier League transfer window closed for new signings last Thursday, the Turkish window remains open until later today.