#3 Tommy Langley — 16 years 09 months 01 days
Tommy Langley had a stellar and lengthy career with the Blue outfit. He joined the West London club in 1974 and remained with them until 1980. Langley played over 152 games for Chelsea during his tenure and netted 43 times.
The striker joined Chelsea as a trainee and appeared for the first time in 1975 against Leicester City. At that time, he was just three months away from turning 17. Unfortunately, Tommy Langley's debut season at the club coincided with their relegation.
Their comeback season (1977-78) was sensational for the forward, who netted 13 goals to become the team's top scorer. Chelsea were once again relegated the following season but Langley stood out by scoring 16 goals throughout the season.
His 16 goals equalled thrice of any of his other teammates' tally. Tommy joined QPR in 1980 for regular top-flight football.
#2 Michael Woods — 16 years 09 months

Michael Woods was a hot property during his youth days. Many Premier League clubs wanted him by their side but it was Chelsea who won the bid. Woods turned down a scholarship from Leeds United to join Chelsea. The move created some rift between the two sides and had to be settled out-of-court.
Woods spent his initial time with the club's reserve squad. He eventually earned a place in the team on 6 January 2007. The midfielder marked his debut at Stamford Bridge in Chelsea's third-round fixture of the FA Cup. Michael Woods made only a couple of FA Cup appearances for Chelsea.
His injury-laden stint denied him a spot in Chelsea's league games. However, the youngster was a permanent member of the Chelsea reserves.
#1 Ian Hamilton — 16 years 04 months 15 days

Ian Hamilton is not just the youngest-ever Chelsea debutant but also the youngest-ever goal scorer for the club. He managed to score on his debut and thus created massive hype around him. Hamilton achieved this feat on 18 March 1967 against rivals Tottenham Hotspur.
Hamilton fell down the pecking order and joined Southend United until the end of the season. The midfielder joined Aston Villa and began a lengthy tenure with them. Hamilton donned the Villa jersey for over 208 games across seven seasons.
After leaving Aston Villa, Hamilton remained in England for another two seasons. He eventually left for the USA in 1978. After his playing days, Hamilton dedicated his life to coaching.