Khamis made his international debut at the 2011 World Youth Championships in Athletics. There he ran in the heats of the 400 m hurdles and set a personal best of 54.27 seconds over the youth height barriers. He also was part of Bahrain's Swedish medley relay team. At the 2012 Asian Junior Athletics Championships – despite winning his heat in a best of 52.67 seconds – he faltered in the 400 m hurdles final and finished last. He also competed at the 2012 World Junior Championships in Athletics, running in the heats only.