Mason and Christian Eriksen were denied late on by fine stops from keeper Ciprian Tatrusanu.
Boss Mauricio Pochettino said: “I’m happy for the effort. The players were fantastic and now we need to recover our energy for Sunday’s match against Swansea.
“We showed character and played very well.
“For me it wasn’t a yellow card for Dele. He was calm against Crystal Palace and today and it was another good performance from him and the team.”
TOTTENHAM (4-2-3-1): Lloris; Trippier, Alderweireld, Wimmer, Davies; Dier, Mason (Winks 87); Lamela (Onomah 75), Alli (Bentaleb 84), Eriksen; Chadli.
Subs: Vorm, Rose, Son, Carters-Vickers.
FIORENTINA (4-3-3): Tatarusgani; Tomovic, Rodriguez, Astori, Alonso; Vecino, Badelj (Fernandez 82), Valero (Blaszczykowski 74); Bernardeschi, Kalinic, Ilicic (Zarate 62).
Subs: Lezzerini, Satalino, , Pasqual, Babacar.
REFEREE: Ovidiu Hategan (Romania).