Moon was born in Los Angeles, California, as the middle child amongst six sisters. He decided early on that he could play only one sport in high school. He chose not only to play football but to be a quarterback since he found that he could throw a football longer, harder, and straighter than anyone he knew.
He enrolled at Alexander Hamilton High School, using the address of one of his mother's friends to gain the advantages of a better academic and athletic reputation than his neighborhood high school could offer. He had little playing time until his junior year, when he took over as varsity starting quarterback. In his senior season, they reached the city playoffs, and Moon was named to the all-city team
He was recruited by a number of colleges, but some wanted to convert Moon to another position as was the norm for many major colleges recruiting high school quarterbacks. Moon decided to attend West Los Angeles College in 1974–75 where he was a record-setting quarterback. After Moon showed his ability at West L.A., Offensive Coordinator Dick Scesniak of the University of Washington was eager to sign the rifle-armed Moon. Moon was adamant that he play quarterback and considered himself to be perhaps a slightly above-average athlete who was either too small, too slow, or not strong enough to play other positions. The Huskies went 11–11 in Moon's first 2 seasons as a starter; but during his senior year, Moon led the Don James coached Huskies to a 27–20 win over the favored Michigan Wolverines in the 1978 Rose Bowl and was named the game's Most Valuable Player on the strength of two short touchdown runs and a third quarter 28-yard (26 m) touchdown pass to wide receiver Robert "Spider" Gaines.
Moon's decision to enter the NFL touched off a bidding war for his services, won by the Houston Oilers. However, with the NFL field being so much shorter and narrower than the CFL's, Moon had a difficult adjustment period. Even so, he still threw for a franchise record 3,338 yards (3,052 m) in his first season with Oilers in 1984. It was only in 1986 when Oilers head coach Jerry Glanville found ways to best utilize Moon's strong arm that he began having success. In 1987, a season shortened by a players' strike that eliminated the third week of the regular NFL season, the Oilers posted a 9–6 record. It was the Oilers' first winning season since 1980, when Bum Phillips was the head coach and Ken "The Snake" Stabler was the quarterback. Moon then passed for 237 yards (217 m) and a touchdown while leading the Oilers to a 23–20 overtime win over the Seattle Seahawks in the wildcard round of the playoffs in his first NFL postseason game.
In 1990, Moon led the league with 4,689 passing yards. He also led the league in attempts (584), completions (362), and touchdowns (33), and tied Dan Marino's record with nine 300-yard (270 m) games in a season. That included throwing for 527 yards (482 m) against Kansas City on December 16, 1990, the second most passing yard ever in a single game. The following year, he again led the league in passing yards 4,690. At the same time, he joined Marino and Dan Fouts as the only quarterbacks to post back-to-back 4,000-yard (3,700 m) seasons. Moon also established new NFL records that season with 655 attempts and 404 completions. In 1991, Moon threw for a career-high 655 passes.
In 1992, Moon played only 11 games due to injuries, but still managed to lead the Oilers to a 10–6 record, including a victory over the Buffalo Bills in the final game of the season. Moon and the Oilers then faced the Bills again in the first round of the AFC playoffs. Aided by Moon's 222 passing yards and 4 touchdowns in the first half, Houston built up a 28–3 halftime lead, and then increased it to 35–3 when Buffalo quarterback Frank Reich's first pass of the third quarter was intercepted and returned for a touchdown. But the Bills managed to storm back with 5 unanswered second half touchdowns to take a 38–35 lead with time running out in the final period. Moon managed to lead the Oilers on a last second field goal drive to send the game into overtime, but threw an interception in the extra period that set-up Buffalo kicker Steve Christie's game winning field goal. It was the largest comeback victory in NFL history and is now known in NFL Lore simply as The Comeback. Moon finished the game with 36 completions for 371 yards (339 m) and 4 touchdowns, with 2 interceptions. His 36 completions remain an NFL postseason record.
As a Houston Oiler, Moon set a franchise record for wins with 70, which stood until 2004, long after the team had become the Tennessee Titans.
He was traded to the Minnesota Vikings after the season, where he passed for over 4,200 yards (3,800 m) in each of his first two seasons, but missed half of the 1996 season with a broken collarbone. Moon then signed with the Seattle Seahawks as a free agent. On September 14, 1997, Moon became the first player over 40 years old in NFL history to score a touchdown. After a two year stint in the Pacific northwest, an aging Moon signed as a free agent with the Kansas City Chiefs as a backup in 1999. He played in only three games in 2 years with the Chiefs before announcing his retirement in January 2001.
Combining his NFL and CFL stats, Moon's numbers are nearly unmatched in professional football annals: 5,357 completions in 9,205 attempts for 70,553 yards (64,514 m) and 435 touchdowns. Even if his Canadian League statistics are discounted, Warren Moon's career is still exceptional: 3,988 completions for 49,325 yards, 291 touchdown passes, 1,736 yards (1,587 m) rushing, and 22 rushing touchdowns. Warren Moon also holds individual NFL lifetime records for most fumbles recovered 56 and most fumbles made 162. Moon was in the top 5 all-time when he retired for passing yards, passing touchdowns, pass attempts, and pass completions.
During his NFL career, Warren Moon was named to nine Pro Bowl games (1988–1995, 1997). Moon currently works as a broadcaster for the Seattle Seahawks on both TV and radio. On the radio, he is co play-by-play announcer with former Seattle Seahawks receiver Steve Raible, who is the lead play-by-play announcer and evening anchor/sports anchor for KIRO-TV in Seattle. He was elected into the Pro Football Hall of Fame in 2006, becoming both the first Canadian Football Hall of Famer, first undrafted quarterback and the first African-American quarterback to be so honored. Moon was elected in his first year of eligibility. The Tennessee Titans retired his number at halftime on October 1 vs the Dallas Cowboys. Moon also holds the little known record for being the oldest player to throw a touchdown pass in overtime (38 years, 359 days).