The popular tourist attraction on Castle Hill has submitted plans that will see renovations to the Discovery Centre and the Queen Mary restaurant.
The Elephant House and the Tropical Bird House will also be upgraded and restored under a scheme put forward to Dudley Council.
A planning statement on behalf of Dudley Zoo and Castle says: "The scheme proposes to restore, renovate and reconfigure the existing Grade II and II* Listed buildings and provide new uses for these underused buildings."
Work to the Grade II-listed Queen Mary, formerly the Castle restaurant, will see outbuildings demolished and repairs to the roof, windows, ceilings and doors.
The Grade II-listed Discovery Centre, which was originally the Moat Cafe before operating as an education centre, is said to be in "poor condition" due to lack of use and in need of a major overhaul.
The statement says: "The building's use will be relocated to a purpose built facility and the Moat Cafe returned to provide support to the Queen Mary."
The Grade II*-listed Tropical Bird House – which has been out of use for years – will be "stripped out" and repaired ahead of its reopening as a "mixed use building that can allow for adaptation to suit a range of activities".
According to the statement the Grade II-listed Elephant House has fallen into disrepair since it ceased to house elephants in 2003.
It will undergo a "strip out and repair", with bosses said to be considering using it as an extension to the monkey enclosure.
The statement concludes: "The proposed improvements will help to better the current state of the buildings and will conserve a unique set of structures that otherwise would go into disrepair and become structurally unstable.
"The overall impact whilst positive will involve intervention and alteration of existing fabric which should be kept to a minimum causing less than substantial harm to most cases.
"The overall impact is positive and should therefore be supported to ensure the sustainability of the structures and a positive future."