Not widely sought by the NFL, Boozer was drafted by the Jets, who were assembling a team of talented and enthusiastic players under George Sauer and Wilbur “Weeb” Ewbank. The team already had fullback Matt Snell and figured Boozer to be paired with him at halfback. Sharing the job with Bill Mathis as a rookie, Boozer worked hard and became a starter in 1967. His ability to block with intensity earned him a league-wide reputation.

In 1967, with Snell injured, the Jets turned to Boozer as a rusher. In the first half of that season, Boozer displayed talent that drew comparisons to Gale Sayers. He often broke tackles and excelled in the open field. He had ten touchdowns by mid-season and appeared ready to easily surpass the league record, but then suffered a devastating knee injury against the Kansas City Chiefs that completely altered his career. Despite playing just half that year, he still led the AFL in rushing touchdowns for the season.

Boozer’s work ethic further revealed itself over the next two seasons. No longer a breakaway runner, he changed himself into more of an outstanding blocker and goal-line touchdown scorer. Ewbank utilized Boozer in pass blocking schemes then new to football. In blocking for both Snell and Joe Namath, Boozer was part of two outstanding teams that narrowly lost just three games in 1968 and went 10–4 in 1969. Boozer and Winston Hill were the blockers during Snell’s famous touchdown run against the Baltimore Colts in Super Bowl III. Boozer’s blocking freed Snell often that day for effective running that was key to the legendary 16–7 win.

Namath turned to Boozer more as a third-down pass catcher in 1970. In 1971, with Snell down again, Boozer took up the slack with a career-high in carries.

In 1972, with Joe Namath back from injuries himself, the Jets rated the top offense in football. Boozer’s ability to block and score near the goal line impressed many as he led the NFL in rushing touchdowns for most of the year before injuries stopped him with 11 touchdowns in 11 games.

In 1973, he was again the main back with 831 yards rushing before taking a spot next to John Riggins in 1974. Boozer scored the first regular-season overtime (“sudden death”) touchdown in NFL history on a short pass from Joe Namath in 1974 to beat the cross-town rival New York Giants, beginning an improbable six-game winning streak for the previously 1–7 Jet squad.

Boozer is a member of The Pigskin Club Of Washington, D.C. National Intercollegiate All-American Football Players Honor Roll. In 2010, he was inducted into the College Football Hall of Fame. The Jets inducted him into their Ring of Honor in 2015. He was inducted into the Suffolk Sports Hall of Fame on Long Island in the Football Category with the Class of 1996.