He caught the winning touchdown pass thrown by quarterback Joe Montana in the NFC Championship Game on January 10, 1982, against the Dallas Cowboys.

Clark played college football for the Clemson Tigers and was selected by the 49ers in the tenth round of the 1979 NFL draft.

[7][8] At 6 ft 4 in (1.93 m), Clark's first love was basketball, but he accepted a scholarship to play college football at Clemson University.

As a sophomore, he was named the starter at strong safety, but he disliked the position and left school to go back to his hometown in Charlotte instead.

In Clark's senior season in 1978, the Tigers were 11–1, won the Gator Bowl over Ohio State, and finished sixth in the final AP poll.

At Clemson, Clark wore #30, posting only 33 catches for 571 yards, three touchdowns and a 17.3-yard average (seventh in school history).

[11] Unheralded as a collegian playing alongside wide receiver Jerry Butler, Clark felt fortunate to get to the NFL.

[13] New head coach Bill Walsh had visited Clemson to scout quarterback Steve Fuller, Clark's roommate.

When the 49er contingent arrived on campus, Clark answered the phone by chance on his way out to play golf and was convinced to participate as Fuller's pass catcher at the workout, where Walsh was impressed with his receiving skills.

[15] But they soon greatly improved, winning the Super Bowl at the ends of the 1981 and 1984 seasons, and, starting in 1981, making the playoffs every year Clark was with them except 1982.

On 3rd-and-3, Clark leaped and caught a 6-yard pass from quarterback Joe Montana in the back of the end zone to tie the score, and Ray Wersching's extra-point kick advanced the 49ers to Super Bowl XVI.

[24] In the 2018 NFL Films documentary Dwight Clark: A Football Life, he was quoted as saying that it was probably a mistake to have accepted the position.

[27] Clark joined his 49er teammates Joe Montana, Ronnie Lott, and Riki Ellison in performing backup vocals on Huey Lewis and the News hit songs "Hip to Be Square" and "I Know What I Like" for the band's Fore!

[11] On March 19, 2017, Clark announced that he had been diagnosed with amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease.