With second-placed AC Milan only able to draw at home to Sampdoria upon the resumption of the season from the international break, Antonio Conte's side was gifted the chance to tighten its grip on top spot.
It duly seized on the opportunity with a ninth successive league win, producing a solid display on the road to move a step closer to a first league title since the 2009-2010 season.
Both teams had strong penalty claims prior to Lukaku's goal in the 31st minute, the striker on hand to tap in the rebound having seen his initial header kept out by a combination of goalkeeper and crossbar.
Federico Ravaglia reacted superbly to parry the attempt up into the air, only to see it loop onto the bar and then drop kindly for Lukaku to prod across the line for his 20th league goal of the season.
Andrea Ranocchia and Lautaro Martinez went close to adding to the advantage prior to the interval, while the latter hit the foot of Ravaglia's left-hand post with a curling effort from just outside the penalty area in the early stages of the second half.
Bologna made sure Inter never felt too comfortable so long as the lead remained at one, though too often the hosts failed to work Samir Handanovic when well positioned to do so.
The Inter captain had been fortunate to see an attempt from Jerdy Schouten go over the top after slipping from his grasp in the opening half, but he was only called on to make two saves throughout the contest.
While the visitors were wasteful themselves at times, managing to get just three of their 14 attempts on target, Lukaku could hardly have missed when presented with the opportunity from which he secured three more vital points for his side.
Lukaku's scoring feats have played a crucial role in helping Inter seize control of the title race, with the Belgian becoming only the seventh player to make it to 20 goals in back-to-back league campaigns in the club's history.
"I'm really happy with the win today; it was a complicated game. We took a big step and need to continue down this road," Lukaku, who was signed from Manchester United in 2019, said.
"It's a great moment for me – I made the right decision coming here.
"I'll do everything I can to help the team because I'm nobody without my team-mates. The group is the most important thing. We have our aim and need to keep this up."
Inter plays its game in hand in midweek, hosting Sassuolo at San Siro on Thursday (AEDT).