However, a impressive performance at the NFL's combine put him on the Dolphins radar and he was selected by Miami in the 2nd round of the 1982 NFL Draft.
From that beginning, Duper emerged to become the Dolphins all-time leader in receiving yardage with 8,869 yards and in total yards from scrimmage with 8,859. The owner of four team records, Duper also ranks second in all-time receptions with 511, third in career receiving touchdowns with 59 and holds three of the top seven single-season receiving yardage totals in team history. Duper also holds team records for the most 100-yard receiving games in a career (28) and a season (8 in 1986).
Duper teamed with Mark Clayton, his teammate for 10 of his 11 seasons, to form one of the NFL’s most prolific receiving combinations, “The Marks Brothers.” Duper was counted on to supply the Dolphins with big plays and he delivered, averaging the second-highest average yards per catch in team history (17.4) and catching the three longest pass plays of Dan Marino’s career, two 85-yard touchdown catches in 1983 and 1986 and an 80-yarder in 1984. A three-time Pro Bowl selection (1983-84, 1986), Duper was chosen as the Dolphins Outstanding Receiver three times (1983, 1986, 1990), was named All-AFC in 1984 and was chosen as AFC Offensive Player of the Week in 1987.
Mark Duper was inducted along with Clayton into the Miami Dolphins Honor Roll on December 15, 2003.