Armed Forces Minister Mark Francois told the Commons an order has been made to allow reservists to be called for service at the summer sporting competition in Glasgow.
The games take place in the Scottish city from July 23 until August 3.
In a written statement, Mr Francois said: "In providing venue security support to the Police Service of Scotland and other civil and Commonwealth Games authorities, defence will contribute up to 2,000 military personnel, of which up to 400 will come from the reserve forces.
"We plan to call out only willing and available reservists, who have the support of their employer."
The call-out order took effect yesterday and ends on August 6.