Playing in his fifth first-class match, the 24-year-old looked in sublime form during his 176-run-knock that was laced with 29 boundaries.
He occupied the crease for nearly six hours to help Bengal recover from a jittery 44 for 2 after they were put into bat.
Raman first built the innings with Kaushik Ghosh (27) in a 92-run third wicket partnership and then shared 163 with skipper Manoj Tiwary, who remained unbeaten on 78 (8x4, 1x6).
Himachal Pradesh grabbed the prized wicket of Test wicketkeeper Wriddhiman Saha (2) with the penultimate ball of the day when bad light stopped play in the 86th over.
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Tiwary had Shreevats Goswami (0 batting) who is yet to open his account.
Raman, who shifted base to Kolkata from his hometown New Delhi in 2012-13, made first-class debut against Mumbai last season and was dismissed in the 90s twice including on 94 against Chhattisgarh in the last match.
Playing at the Eden Gardens at senior level for the first time, Raman finally got to the milestone in 141 balls, with a pull through fine-leg boundary off Pankaj Jaiswal in the second session.
He thanked skipper Tiwary for his support during as he approached century.
"I was nervous in the 80s but skipper (Tiwary) supported me well and I finally got to the mark. He (Tiwary) pushed me for a double but it happens. I'm happy with my knock."
Brief Scores
In Kolkata: Bengal 306/5 in 86 overs (Abhishek Raman 176, Manoj Tiwary 78 batting) vs Himachal Pradesh.
In Nagpur: Vidarbha 259/3 in 90 overs (Faiz Fazal 128, Sanjay Ramaswamy 55) vs Services.