He stayed with the Dresden club until his retirement as a player in 1988 having played in 366 East German first division DDR-Oberliga matches, scoring 49 goals.

Häfner was part of four DDR championship and FDGB Pokal (East German Cup) winning teams there.

Between 1971 and 1984 he was capped 58 times for the East Germany national team, scoring 5 goals, and was part of the gold medal-winning squad at the 1976 Summer Olympics in Montreal, Canada.

[1] In April 1990, two years after his retirement as a player, Häfner became head coach of Dynamo Dresden, replacing Eduard Geyer.

The following season, despite the sale of star players Ulf Kirsten and Matthias Sammer, Häfner guided the Dresden team to a second-place finish in the final DDR-Oberliga season before the merger of the football competitions of East and West Germany following the reunification of the country, qualifying the club for the first division Bundesliga.