After a successful career at the high school level, he served as the head coach of the University of Maryland football team from 1969 to 1971.

Lester attended West Virginia University where he was a three-sport athlete and earned letters in football, baseball, and basketball.

[2] He played college football under famed coaches Bill Kern and Dudley DeGroot as an end in 1948 and participated in the 1949 Sun Bowl.

[2] In 1949, Lester played football for the Paterson Panthers of the American Association, a farm team of the Philadelphia Eagles.

[2][5][6] Lester served as the head football coach at Richard Montgomery High School in Rockville, Maryland, from 1959 to 1968.

[7][8] In a time before Maryland hosted high school football playoffs, Lester's teams were considered some of the best in the state.

[12] Lester's philosophy was explained by the Maryland sports information director Jack Zane: "The pass should open up the defense for the running game.

"[12] In the sixth game of his first season, Maryland's starting quarterback, junior Dennis O'Hara, was injured in a loss at South Carolina, and was replaced by sophomore Jeff Shugars.

[13] Lester attributed Maryland's football woes to the turnover at head coach and lack of depth because of recruitment shortcomings.

"[16] In 1971, some observers considered Maryland, which returned 37 lettermen, to be the dark horse in the Atlantic Coast Conference (ACC).

The Star-News called it the most stunning of five upsets in the ACC teams' opening weekend, rating it ahead of NC State's loss to Kent State, Virginia's loss to Navy, South Carolina's win against Georgia Tech, and Duke's win against Florida.

[17] Maryland won the following week against NC State, but then dropped five straight before beating the Virginia Military Institute on Homecoming.

"[21] One of Lester's lasting contributions was the recruitment of future Maryland and NFL star Randy White.

[23] In 1972, Lester returned to the interscholastic ranks as a head coach at Paint Branch High School in Burtonsville, Maryland, which awarded him a ten-year contract.

[24] In 1989, he earned his 200th win as a high school coach when Magruder defeated Einstein, 24–0, bringing his interscholastic record to 200–61.

[28] In 2002, Richard Montgomery High School renamed its athletic field Roy Lester Stadium in his honor.