NFL.com provides a list of Super Bowl winners from the 1970s. The Pittsburgh Steelers won three Super Bowls in the '70s. The Miami Dolphins and the Dallas Cowboys both won two Super Bowls in the '70s.
The Steelers won Super Bowl IX in 1975 against the Minnesota Vikings, Super Bowl X in 1976 against the Cowboys and Super Bowl XIII in 1979 against the Cowboys again.
The Dolphins won two back-to-back Super Bowls in 1973 and 1974. They defeated the Washington Redskins in Super Bowl VII and the Minnesota Vikings in Super Bowl VIII. The Cowboys defeated the Dolphins in Super Bowl VI in 1972, and they also won Super Bowl XII in 1978 against the Denver Broncos.
Other Super Bowl winners in the '70s were the Kansas City Chiefs in 1970, the Baltimore Colts in 1971 and the Oakland Raiders in 1977.