Dhawan, who is a eyeing a comeback in the Champions Trophy in June, helped India B post 327 for eight in 50 overs.
The others who contributed to the competitive total were captain Parthiv Patel (50) and Jharkhand batsman Ishank Jaggi (53).
India B put up an all-around effort with the ball to bundle out India A for 304 in 48.2 overs as Ambati Rayudu's 92 went in vain. Pacer Dhawal Kulkarni and ambidextrous spinner Akshay Karnewar stood out for India B, taking three wickets each.
Dhawan delivered knowing the importance of the only 50-over domestic tournament to be played before the Champions Trophy in England. His 122-ball innings comprised 13 fours and three sixes.
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The southpaw last played for India in the ODI series against England in January after being dropped from the Test team.
It is an important tournament for another big player, Harbhajan Singh, who is captaining the India A squad. He leaked 72 runs in the 10 overs he bowled today and failed to pick up a wicket.