We took the lead six minutes into the first leg of our Round of 32 tie when Roberto Soldado volleyed in from Paulinho's corner.
The visitors equalised half an hour later when Jose Maria Basanta bundled in from close range after a free-kick from Matias Fernandez caused problems for goalkeeper Hugo Lloris at his near post.
It means the tie is finely balanced heading into next Thursday's second leg in Italy.
Spurs (4-2-3-1): Lloris, Walker, Vertonghen, Fazio, Davies, Bentaleb, Paulinho (Mason 84), Townsend (Lamela 73), Eriksen, Chadli (Kane 66), Soldado. Substitutes (not used): Vorm, Rose, Dier, Dembele.
Fiorentina (3-5-2): Tatarusanu, Savic, Gonzalo Rodriguez, Basanta, Joaquin, Fernandez, Pizarro, Valero (Badelj 78), Pasqual (Alonso 66), Salah, Gomez (Ilicic 84). Substitutes (not used): Neto, Richards, Aquilani, Babacar.
Goals: Spurs – Soldado 6; Fiorentina – Basanta 36.
Yellow cards: Spurs – Soldado; Fiorentina – Gonzalo, Savic.
Referee: Carlos Velsaco Carballo.