Sehwag, who turns 24 later this month, cracked 24 fours and three sixes to put India in control at 278 for two at the close of the first day’s play.
It was the Delhi opener’s third Test century in 10 matches and beat his 106 against England at Trent Bridge this year.
Local boy Sanjay Bangar played the anchor role scoring 55 in a first-wicket stand of 201, the best ever at Bombay’s Wankhede stadium and beating the 192 between Sunil Gavaskar and Chetan Chauhan in 1979-80 against Australia.
Bangar held off the West Indies bowlers for more than four hours in hot and humid conditions before falling for 55, flicking paceman Mervyn Dillon to square leg where Ramnaresh Sarwan took a low catch diving to his right.
It was Bangar’s second Test half-century in his eighth match and seems to have put India’s perennial opening worries to rest for a while.
Sehwag followed soon after Bangar, edging Dillon to wicket-keeper Ridley Jacobs after a 207-ball knock in the first of a three-Test series.
At stumps Rahul Dravid had built a fluent 28 with hometown hero Sachin Tendulkar on 35, including five fours. Dillon took two for 30 off 16 overs.
Sehwag, opening the batting for the first time at home after his success in the four-Test series in England, looked uncomfortable early on against left-arm seamer Pedro Collins.
Runs came in a trickle as the ball kept low or shot up suddenly on a freshly laid wicket that had a tinge of green.
Sehwag was lucky on nought when he was rapped on the pads in front of the wicket by Collins off a no-ball.
But the stocky right-hander soon opened up.
He raised his half century off 85 balls, cutting Collins to the third man fence for fours off successive balls and then went on a rampage in the second session.
There was a sniff of a chance on 59 when he cut Dillon just over the head of Collins at third man for four. Sehwag hit Nagamootoo for a straight six and raised his 100 off 138 balls pulling occasional seamer Wavell Hinds to mid-wicket.
His second six, over long on off Ryan Hinds, landed in a stand named after his childhood hero Tendulkar.
Bangar got a life on 53 when Cuffy dropped a simple chance at mid-off off the bowling of captain Carl Hooper, who had no luck on the first day of his 100th test.
Paceman Javagal Srinath returned for India in this match after reconsidering his decision to retire from tests, made four months ago.
West Indies, who beat India 2-1 in the Caribbean earlier this year, managed to draw a three-Test series when they were last in India in 1994-95.
INDIA (1st Innings):
S.B. Bangar c Sarwan b Dillon 55
V. Sehwag c Jacobs b Dillon 147
R.S. Dravid not out 28
S.R. Tendulkar not out 35
EXTRAS (LB-5, W-1, NB-7) 13
TOTAL (for two wkts, 90 overs) 278
FALL OF WKTS: 1-201, 2-213.
TO BAT: S.C. Ganguly, V.V.S. Laxman, P.A. Patel, Harbhajan Singh, A.R. Kumble, Zaheer Khan, J. Srinath.
BOWLING (to-date): Dillon 16-6-30-2 (1w); Collins 15-6-38-0 (3nb); Cuffy 15-3-42-0; Nagamootoo 21-4-70-0 (3nb); Hooper 7-2-34-0; W.W. Hinds 4-0-11-0; R.O. Hinds 9-0-39-0 (1nb); Gayle 2-1-3-0; Sarwan 1-0-6-0.
WEST INDIES: W.W. Hinds, C.H. Gayle, R.R. Sarwan, S. Chanderpaul, C.L. Hooper, R.O. Hinds, R.D. Jacobs, M.V. Nagamootoo, M. Dillon, P.T. Collins, C.E. Cuffy.
UMPIRES: E.A.R. de Silva (Sri Lanka) and D.R. Shepherd (England).
TV UMPIRE: I. Sivaram (India).
MATCH REFEREE: M.J. Procter (South Africa).—Reuters