The 19-year-old becomes Darren Way’s fourth January signing, and will remain at Huish Park until the end of the season.
Harrison, who has risen through the ranks at White Hart Lane, has been prolific for the Under-21s and made his professional debut for Spurs in the 2-1 defeat to Liverpool in the EFL Cup in October last year.
Highly-rated by Tottenham manager Mauricio Pochettino, Harrison was also in the Premier League outfit’s squad for their Europa League clash with Qarabag in November 2015.
With the teenager eligible to play in Town’s match against Blackpool on Saturday, Way was delighted with his latest arrival.
"We played against Spurs in pre-season and Shayon played very well and caught the eye," he said.
"He’s been very close to the first team and is someone Pochettino rates very highly.
"We know Tottenham have an unbelievable desire and work ethic, which are massive attributes needed to play for Yeovil Town.
"Shayon will follow in the footsteps of the likes of Ryan Mason, Steven Caulker and Andros Townsend, so we look forward to continuing the relationship with Spurs."
Harrison will wear the number 39 shirt during his time at Huish Park, with everyone at Yeovil Town Football Club wishing Shayon all the best during his time in Somerset.