The boys' 800 metres at the 2011 World Youth Championships in Athletics was held at the Stadium Lille Métropole on 6, 7 and 9 July.

[1] Prior to the competition, the following records were as follows.

During the competition, Leonard Kirwa Kosencha lowered Belal Mansoor Ali's world youth best to 1:44.08, thereby establishing a new championship record, too.

Qualification rule: first 3 of each heat (Q) plus the 3 fastest times (q) qualified.

[2] Qualification rule: first 2 of each heat (Q) plus the 2 fastest times (q) qualified.