Construction and fit-out costs for the high-tech theatrette totalled almost $235,000 while the annual cost of having it on stand-by is running at about $100,000.
The government is leasing the premises, next to the Department of Foreign Affairs and Trade’s aid office in Canberra, until June 2016.
It is also paying $10,000 a month to hire audio visual equipment on top of a $30,000 bill for rented stage lights, according to documents obtained by AAP under Freedom of Information.
The heavily-redacted documents reveal the facility was ready for media briefings in October 2013, but it has never been used for that purpose.
It is understood the room was intended for Operation Sovereign Borders media briefings presented by Immigration Minister Scott Morrison until late last year.
Instead, the weekly briefings were held at commonwealth offices in Sydney.
The briefings ended in December, coinciding with reports of asylum-seeker boat turn-backs which the government refused to discuss.
In Canberra, Mr Morrison has mostly used Parliament House facilities for border protection-related press conferences.
In mid-July, he launched a national border targeting centre at the Customs Border Protection headquarters, located across the road from the briefing room.
He addressed reporters after the launch in a Customs room.
The unused media centre has large LED monitors, a projector, spotlights, two podiums with microphones, audio splitters and space to fit four television camera tripods and seating for 20 journalists.
Invoices show $800 was spent on a single door knob.