Indiana took a 19-point lead in the second period, then fought off a comeback by Atlanta that saw the Hawks close within three points with 2:41 to play.
West then scored on a layup with 2:14 left to give the Pacers a 78-73 lead and the Hawks went without a point the rest of the way.
Indiana eliminated Atlanta in six games with Friday's victory being the only win by the road team during the Eastern Conference quarterfinal series.
The Pacers scored the final six points of the first half to take a 37-29 lead at the break, then continued their surge in the third quarter until they had created a 21-4 run that appeared to have put the game away.
Atlanta, however, came back to make a game of it despite shooting just 33 percent from the field and making a mere 3-of-19 from 3-point range.