Renfro's best season came as a senior, posting 50 receptions for 794 yards, including a school and a Southwest Conference single-season record with 10 receiving touchdowns.
Down 17–10 late in the third quarter of the AFC Championship game against the Pittsburgh Steelers, a Dan Pastorini pass to Renfro for an apparent tying touchdown was ruled not a catch, possibly costing the Oilers a chance for victory and a trip to the Super Bowl.
In 1983, Renfro did not play until the fifth regular season game while he was recovering from hepatitis and was eventually placed on the injured reserve list with a left knee injury on November 28.
In 1984, Renfro was acquired by the Dallas Cowboys after starter Drew Pearson suffered a career-ending car accident.
In the NFC Eastern Division title-clinching win against the Giants later in the year, he caught four receptions for 123 yards and two touchdowns, including a 58-yard catch.
In 1986, Renfro was limited with a shoulder injury suffered in the first preseason game against the Chicago Bears and spent the first four weeks of the season on the injured reserve list.
In the eighth game, against the New England Patriots, on a fourth-and-13 situation with 1:06 minutes remaining, he had a 43-yard catch to set up the tying field goal in a 23–17 overtime win.
On Thanksgiving Day, against the Minnesota Vikings, he had seven receptions for 100 yards and three second-half touchdowns, in a game the Cowboys lost 44–38 in overtime.
[9] His father, Ray Renfro, was a four-time world champion All-Pro wide receiver for the Cleveland Browns from 1952 to 1964, and was once considered the fastest man in football.
Mike was the water boy for the Cowboys that season and wears his father's Super Bowl ring today.
He attended Carroll Senior High School, where he helped lead the team to state championships as a wide receiver in 2004 and 2005.
[11] Renfro served as the ballboy for the Dallas Cowboys, during the time his father worked on the team's coaching staff from 1968 to 1972.