Defender Carlos Augusto headed in from a corner early in the second half before Marcus Thuram wrapped up a fourth successive league win with a thumping finish in stoppage time.
Inter goalkeeper Yann Sommer made a crucial save on the hour to deny Nico Paz an equaliser as Simone Inzaghi's side showed signs of weariness at the San Siro in what was their third outing in a week.
Thuram's goal was his 12th of the season and sent him level with Atalanta striker Mateo Retegui for the league lead.
"Marcus is a high-class player who always trains well and has adapted very quickly to the way we play," said Inzaghi.
"You have to congratulate Como for coming here and giving it their all, but we stayed focused and showed great maturity."
Third-placed Inter are a point behind Napoli but have played a game less than the top two teams after their match with Fiorentina was called off at the start of December following Edoardo Bove's sudden collapse.
Reigning champions Inter visit lowly Cagliari this weekend and could put the pressure back on Atalanta, who are away to Lazio in the late game on Saturday.
Como, coached by Cesc Fabregas, slipped a spot to 16th and sit just one point clear of the relegation zone.
Fiorentina lost more ground in the title race after falling to a 2-1 home defeat by Udinese.
Moise Kean's early penalty gave Fiorentina the lead as they sought to shake off last weekend's loss to Bologna that snapped the club's eight-match winning streak in Serie A.
However, Udinese equalised shortly after half-time through Lorenzo Lucca and former France international Florian Thauvin curled in the winner from outside the area.
"The most important thing for me is not the goal but the victory. These are three important points against a very strong team," said Udinese captain Thauvin.
Udinese stayed ninth and are eight points off the European places.
