In a match which was reduced to 45 over-a-side due to a delayed start, Pakistan opted to bat first but failed to capitalise on the advantage.
Led by left-arm seamer Ahmed, India dismissed Pakistan for a mere 197 in 44.1 overs and then surpassed the target in the 34th over itself to fashion a convincing and morale-boosting victory.
At one stage, Pakistan were cruising at 75 for one before Ahmed wreaked havoc with an impressive spell of five for 30 and they lost their last nine wickets for 122 runs.
Chasing a modest target, big-hitting Sarfaraz smashed 81 off 68 deliveries with 12 boundaries and a six to seal an easy win for India.
Three-time champions India will open their campaign against Ireland in Group D on January 28.