Taylor was drafted by both the AFL (Chiefs) and NFL (Philadelphia Eagles) in 1965. After a famous "baby-sitting" incident, in which Taylor "escaped" from NFL scouts, he was signed for the Chiefs by their legendary scout Lloyd Wells. Taylor caught five touchdown passes during his rookie year, and followed that up in 1966 by leading the AFL with a 22.4 yd/catch average and finishing second in receiving yards (1,297). At season's end, he was voted First-team All-AFL and was selected for the 1966AFL All-Star team. Taylor led the AFL in receiving touchdowns in 1967 with 11 and led the NFL in receiving yards in 1971 with 1,110. He made the AFC-NFC Pro Bowl twice and in 1971 was named Consensus All-Pro by the Associated Press (AP), the Newspaper Enterprise Association (NEA), the Pro Football Writers Association (PFWA) and Pro Football Weekly. The PFWA also named him First-team All-Pro for the 1972 season. Taylor ranks second on the Chiefs' all-time list in receptions (410), receiving yards (7,306), receiving touchdowns (57) and 100-yard games (20).
Taylor combined with running back Robert Holmes for what was at the time the longest reception in Chiefs history in 1969 when he caught a pass from quarterback Mike Livingston for 79 yards, then lateraled to Holmes, who carried it another 14 yards for a touchdown. However, Taylor's most memorable highlight from that season came in the fourth and final AFL-NFL World Championship Game on January 11, 1970, when he caught a short pass, turned upfield and stiff-armed his way to a 46-yard touchdown in the Chiefs 23-7 upset victory over the NFL's champion, the Minnesota Vikings, who, before Super Bowl IV, had been dubbed by some as "the greatest team in pro football history".
"Otis made my job easy," former Chiefs quarterback and Hall of Famer Len Dawson said. "If you got the pass to Otis, you knew he'd catch it."
On 1 November 1970, the Chiefs led the Oakland Raiders 17-14 late in the fourth quarter, and a long run for a first-down run by Dawson apparently sealed victory for the Chiefs in the final minute when Dawson, as he lay on the ground, was speared by Raiders’ defensive end Ben Davidson, who dove into Dawson with his helmet, provoking Taylor to attack Davidson. After a bench-clearing brawl, offsetting penalties were called, nullifying the first down under the rules in effect at that time. The Chiefs were obliged to punt, and the Raiders tied the game on a George Blanda field goal with eight seconds to play. Davidson's hit against Dawson not only cost the Chiefs a win, but Oakland helped win the AFC West with a season record of 8-4-2, while Kansas City finished 7-5-2 and out of the playoffs. The next season, the rule for offsetting penalties was changed to separate penalties during the play, and penalties after the play. The rule change was largely due to this play.