Veretout scored from the spot for the third time in the last five Serie A games after Cengiz Under's backpass was intercepted by Giovanni Simeone and the Argentine went down under a challenge from goalkeeper Robin Olsen.
It was the third penalty against Roma this season and it was questionable if there was any contact although the referee decided against using a VAR review.
Fiorentina kept the lead until the 85th minute when goalkeeper Alban-Marc Lafont attempted to punch away Aleksandar Kolarov's cross and Florenzi tucked away the rebound.
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Lafont made amends five minutes later with a good save to deny Edin Dzeko and preserve Fiorentina's unbeaten home record.
The draw left the teams level on 16 points from 11 games with Fiorentina ahead in sixth place on goal difference.
Roma, missing captain Daniele De Rossi through injury, gave a first Serie A start to 19-year-old midfielder Nicolo Zaniolo.
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