The organisation received a donation of $89,000 through the State Government Lotterywest grants program last April.
The grant was used to fund the new hospital wing and five banks of aviaries.
During the build, volunteers clocked up 1000 building hours and an extra $15,283 from donations to the wildlife centre also went towards the construction.
Dawesville MLA Kim Hames said Mandurah Wildlife Rescue was renowned in the Peel region.
He said rescue president Dot Terry-Bos and her team did fantastic work to rescue, rehabilitate, and release injured or displaced wildlife.
�I was pleased to open the new hospital wing and it is great it is now operational, with the aviaries soon to be complete,� Dr Hames said.
�The rescue centre operates entirely with volunteer help and community support and it appreciates all the help it can get.
�It is often overrun with wildlife and they have been finding it difficult caring for the birds and animals in the same area.�
He said the problem was that birds carried diseases and needed to be kept separate from sick animals.
�It is a relief to the staff that there will be a lot less risk of disease being spread at the centre once the birds and animals are housed separately,� Dr Hames said.
�It is great that the staff now have greatly needed equipment, especially the microscope and computer which will assist significantly in the care of the wildlife.�
If you would like to donate to the wildlife centre or want to volunteer, call 9534 3200.