Inzamam, who made 122 in the first match at Karachi last week, plundered 123 off 121 balls after he won his fourth consecutive toss and elected to bat in the day-night match at the Gaddafi stadium.
India, who trail 1-2 in the five-match series, face a stiff target of 5.9 runs an over under lights in a match the tourists must win to keep alive hopes of a push for victory in Wednesday's last game at the same venue.
Inzamam, who hit nine boundaries and four sixes in his 10th One-day hundred, put on 105 for the fourth wicket with Younis Khan and 70 off 46 balls for the fifth with Abdul Razzaq.
Razzaq pounded an aggressive 32 off 24 balls as Pakistan smashed 95 from the last 10 overs in front of a capacity crowd of 25,000 that included some 4,500 Indians fans.
India began well when left-arm seamer Irfan Pathan dismissed opener Shahid Afridi and the experienced Yousuf Youhana cheaply to reduce Pakistan to 39 for two.
Afridi slashed a short ball to point where Yuvraj Singh leapt high in the air to pluck the ball with both hands.
Youhana, who made nine, survived two confident leg-before appeals in Pathan's fifth over before being finally given out off the last ball of the same over when he shuffled across the line.
Yasir Hameed, fresh from his 98 in the previous match at Peshawar on Friday, helped Inzamam add 50 for the third wicket before a lapse in concentration caused his dismissal.
Hameed made 45 with the help of five boundaries when he charged down the wicket to left-arm spinner Murali Kartik, missed the line and was stumped by Rahul Dravid.
Inzamam, however, cruised along merrily at the other end.
He hit a six and two fours in the 33rd over bowled by Yuvraj and then welcomed Laxmipathy Balaji's second spell by lofting the first delivery over the long-on ropes.
Younis Khan made 36 in the century stand with his captain when he swept Kartik down Pathan's throat at deep square-leg to make Pakistan 194 for four in 39 overs.
Inzamam fell in the 46th when he was bowled by Balaji while trying to pull from outside the off-stump.