Branch was also a standout track athlete. He set the University of Colorado at Boulder and NCAA Championship record in the 100 meters with a time of 10.0 seconds at the 1972 NCAA championships semifinal in Eugene. Branch placed 5th in the final with 10.1, and he said "My goal has always been to win the NCAA 100 meter championship. This is my last track meet, since I expect to sign a pro contract with the Oakland Raiders within the next two weeks." (which meant he would not run in the 1972 Olympic Trials). He also posted a personal best of 20.5 seconds in the 200 meters.
Cliff was voted a First team All-Pro in four consecutive seasons (1974–1977) and had 46 receptions in 1976 for 1,111 yards and 12 TDs, averaging 24.2 yards per catch. During this time, Branch was also named to four consecutive Pro Bowls from 1974–1977. In 1974, Branch led the National Football League in both receiving yards (1,092) and receiving touchdowns (13). During the 1983 season, Branch set the Raiders franchise record for the longest TD reception (99 yards), on a pass from Jim Plunkett.
Branch finished his 14 NFL seasons with 501 receptions for 8,685 yards and 67 touchdowns. He also rushed for 70 yards and returned 9 kickoffs for 191 yards.
When Branch retired he led the NFL in post season receptions (73) and yards (1289) for an average of 17.7 yards per catch, Scoring 5 TD's.