Jose Mourinho's reigning champions are looking unstoppable as headers from Walter Samuel and Zlatan Ibrahimovic and a Mobido Diakite own goal gave Inter an easy evening in the capital.
The pressure is now on pursuers AC Milan and Juventus, who play Catania and Lecce respectively on Sunday, not to slip up a week before they meet in a crucial clash at the Stadio Olimpico in Turin.
Despite their lead, Mourinho played down talk of the title.
"The scudetto? Halfway through the season we're nothing, but experience tells me that this is a real team," said the former Chelsea boss.
"It's a pleasure for me to be the coach but I don't want to get too excited right now, we have to keep our feet on the ground. I don't want to be winter champions, I want to be champions in May."
Inter got off to a dream start in the Roman Stadio Olimpico as Samuel headed home a cross from Ghana midfielder Sulley Muntari on two minutes.
Lazio had the better of the rest of the first period but Aleksandar Kolarov and Ousmane Dabo thrashed vicious shots wide while Lorenzo De Silvestri had another deflected just past the post.
Inter goalkeeper Julio Cesar also tipped a shot from Pasquale Foggia onto the outside of the post as the hosts piled forwards, but disaster struck in first half injury time as Diakite inadvertently turned a Maicon cross past Juan Pablo Carrizo in the Lazio goal.
The match was over as a contest ten minutes into the second period as Ibrahimovic headed home an Esteban Cambiasso free-kick, although it looked to have gone in off a defender's head.
Lazio did get the ball in the net direct from a Kolarov free-kick but the referee disallowed the effort because he had blown his whistle for an infringement.
Luciano Spalletti's Roma finished with ten men as they won for the fourth match in a row with French winger Jeremy Menez celebrating a rare start by scoring the only goal of the game with a stunning volley, just days after suggesting he would leave the club he joined in the summer due to his limited starting opportunities.
Chievo remain rooted to the foot of the table while Roma moved up to 12th but crucially they are now only four points off a Champions League qualifying position.
For a team who harboured hopes of winning the title before beginning the season with six defeats in their opening nine matches, they now seem firmly back on the right track.
"Right now I'm just happy to see my players in a good condition psychologically and physically," said Spalletti, referring to their troubles of earlier in the season.
"There was a risk that they would lose their self-belief but instead they reacted in the right way and now we can allow ourselves to aim for something important."
Roma had much the better of a tame opening spell with Menez proving a particular threat. After ten minutes he beat two players as he slalomed into the area but Chievo goalkeeper Stefano Sorrentino was equal to his effort.
On 26 minutes Menez turned creator, dancing into the area and crossing to the edge of the six-yard box where Matteo Brighi somehow failed to score, directing his close range effort straight at the sprawled Sorrentino.
Roma turned the screw after the break and despite Sorrentino coming to the rescue again on 65 minutes to repell a Simone Perrotta volley they went ahead four minutes later.
Once again it was Menez who proved decisive, running onto a header forwards from Daniele De Rossi before steering a delightful right foot volley from 15 yards across Sorrentino and into the far corner.
The only sour note was Brighi's sending off five minutes from time for a second booking.
