In voting results released Wednesday by the league, Conner also was picked as its offensive player of the year. Clemson defensive end Vic Beasley was selected as the defensive player of the year.
Conner received 16 of 55 votes cast by members of the Atlantic Coast Sports Media Association -- three more than Winston, who has guided the Seminoles to a 12-0 record.
Conner led the conference and ranks sixth nationally with 139.6 rushing yards per game. He also scored an ACC-leading 144 points while rushing for a school-record 24 touchdowns and helping the Panthers earn bowl eligibility.
"We are tremendously proud of James and all that he achieved this season," Pitt coach Paul Chryst said. "I know our entire program takes pride in James receiving this prestigious honor."
Beasley, who was third in the overall player of the year voting, had ACC bests of 11 sacks and 18.5 tackles for losses and leads all active players in the FBS with 32 career sacks.
"He came back for his senior year to graduate and to have a great season and improve as an all-around player," Clemson coach Dabo Swinney said. "He has done that. He is a complete player. ... He is the best defensive player in the ACC, and I really feel he is the best defensive player in the nation."
The Associated Press contributed to this report.