Goals from Mario Hermoso and Rodrigo Mora, alongside a Sebastian Walukiewicz own goal, secured all three points for Gian Piero Gasperini's side as they strengthened their position near the top of the Italian league table.
Roma started brightly and threatened through Leonardo Balerdi, whose headed effort was cleared off the line by Duje Caleta-Car.
The home side eventually broke the deadlock in the 27th minute when Hermoso collected a loose ball inside the penalty area and fired a powerful left-footed finish into the net.
Three minutes later, Roma doubled their advantage. Donyell Malen attempted to find the target, but his effort took a decisive deflection off Walukiewicz and ended up in the Sassuolo net.
Roma continued to create opportunities before the interval, with goalkeeper Arijanet Muric making important saves to prevent the deficit from increasing.
Rodrigo Mora completes Roma victory
Sassuolo struggled to find a response after the break as Roma maintained control of the encounter.
The hosts added their third goal in the 58th minute when Rodrigo Mora received the ball outside the penalty area and produced a precise low finish into the corner.
Roma continued to threaten, but Muric made further saves to limit the damage.
Sassuolo, meanwhile, struggled to create clear opportunities and could not find a way past Roma's defence.
Roma move second in Serie A
The victory gave Roma their third consecutive league win and took their points tally to 27 from 11 matches.
They moved into second place, one point behind leaders Lazio, although the standings remained subject to the other teams' fixtures.
For Sassuolo, the defeat extended their difficult run of form and left them facing further pressure to improve their results.
Roma will look to maintain their momentum after the international break as Gasperini continues to build a side capable of challenging for the Serie A title.