Lionel Messi joined FC Barcelona’s youth setup, La Masia, in September 2000, when he moved from Newell’s Old Boys to Barcelona at age 13.

He officially became a Barcelona player when the club agreed to sign him on December 14, 2000, through the famous “napkin contract” written and signed by sporting director Carles Rexach and his representatives. From there, he progressed through the youth ranks and later made his official first-team debut in 2004, but his joining Barcelona dates back to that 2000 youth signing.

TL;DR:

  • Joined Barcelona youth academy: September 2000.
  • Formal agreement to sign him (napkin contract): December 14, 2000.