John Cena joined wwe in the year 2001 . the date is unknown . if you want to read avout him go to this site http://prowrestling.wikia.com/wiki/John_Cena . if you want to read wikia of any other superstar from wwe , tna, ucw , ecw etc. go to http://prowrestling.wikia.com.
Because they offered him a contract
He hasn't actually left.
He Joined on the 27th of June, 2002
John Cena is still in WWE.
John Cena appeared on the Smackdown brand when he joined WWE in the spring of 2002. My Source: My memory.
john cena did get rehired
John Cena's height is six foot one. The is in the WWE.
John cena was a olympic fighter
yes John Cena will win the wwe championship at wrestlemania 29
no John Cena has not been fired from the WWE but he has before but he came back though