A left-hand middle-order batsman, Leon Johnson made his first-class debut for Guyana at 16. He played two matches that season but then had to wait four years for his next opportunities, in the meantime captaining West Indies at the Under-19 World Cup in 2005-06.

When he returned to the Guyana line-up in 2007-08, Johnson had a solid Carib Beer Series and scored 427 runs at 42.70, a consistent effort considering that he did not make a century during the campaign. The promising signs were enough for the West Indies selectors to choose him for the ODI tri-series in Canada later that year. He impressed with a half-century in his second match. He later earned a call-up to the Test squad to New Zealand.