Argentine international defender Nicolas Burdisso headed home Zlatan Ibrahimovich's delightful cross to put Inter in front after 11 minutes.
Cagliari's Honduran striker David Suazo was a potent threat for Inter defenders as he missed two clear chances in the second half.
Dejan Stankovic's almost doubled Inter’s lead in the 74th minute but his long range effort hit the crossbar.
Substitute Santiago Solari sowed a commanding presence with a powerful left-footed strike saved by Cagliari keeper ten minutes from time.
Elsewhere, Roma lost more ground to Inter after they were handed a surprise 1-0 away defeat to Empoli.
Nicola Pozzi notched what proved to be the winner as early as the fifth minute.
Inter are now clear favorites to claim the Scudetto, as they're topping the table with 63 points, a massive 14 points ahead of second-placed Roma.