The Birmingham-based developer and the Defence Infrastructure Organisation have lodged plans for a residential facility for staff working at the Royal Centre for Defence Medicine (RCDM).
This development will provide 180 en-suite bedrooms and support facilities for RCDM personnel based at the city's Queen Elizabeth Hospital in Selly Oak who are currently housed in rented accommodation across the city.
The six-storey building would be adjacent to the A38 Longbridge roundabout.
Mike Murray, senior development surveyor at St. Modwen, said: "The RCDM accommodation will be an important contribution to the evolving and increasingly diverse community at St Modwen's £1 billion regeneration of Longbridge.
"Subject to planning consent being granted by Birmingham City Council's planning committee, construction of the facility will begin this autumn."
The Centre for Defence Medicine was established in Birmingham at the QE in 2001 and became the Royal Centre in 2002.
The decision to make a greater use of NHS hospitals and training facilities led to an open competition in which NHS trusts were asked to bid to host the then Centre for Defence Medicine.
University Hospital Birmingham Foundation Trust was awarded the contract which will last until at least 2045.
The wider redevelopment of Longbridge has already seen a new Sainsbury's, technology centre and Bournville College constructed while the region's largest Marks & Spencer is due to open later this year.