More than 9000 native animals can be saved every year by keeping pets inside, according to an environment management group.
GeoCatch Officer Nicole Lincoln said keeping cats and dogs inside at night keeps them safe from cars, poisoning, fighting with other pets, catching diseases, neighbour disputes and from getting lost.
It comes after TV actor Myles Pollard and other local pet owners saved 'a significant number' of lives by keeping their pets inside for one night, according to Ms Lincoln.
The first ever Pets Night In was held on National Pet Day on April 11 and had 89 pets tucked up inside, after Ambassador Miles Pollard encouraged owners to make the pledge.
Ms Lincoln explained that wildlife were also protected during the 12-hour window, which demonstrates how easy it can be to look after our wildlife beyond Pets Night In.
"If these pet owners continue to keep their pets inside, we can save an estimated 9,570 native animals annually. Image what could be achieved with further pet owners on board" Ms Lincoln said.
With 1,600 cats registered within the City of Busselton, Ms Lincoln said there is a lot of potential to save wildlife from death or injury by keeping them contained.
GeoCatch Chair Felicity Bradshaw said that on average, one roaming cat can kill up to 110 native animals each year.
"Like cats, dogs can also cause harm to wildlife due to their curiosity and predatory instincts, particularly at night when possums are active" said Felicity.
GeoCatch, RSPCA and SAFE Busselton advocate for the full-time containment of dogs and cats, and hope the Pets' Night In has encouraged more people keep their pets inside.
GeoCatch hopes to grow the event in coming years and encourages any organisation or catchment group to be involved.
The pledge page will stay open for those still wishing to pledge beyond Pets Night In, at https://www.geocatch.asn.au/living-with-possums/petsnightin/
There are resources available to support pet owners at geocatch.asn.au and swccnrm.org.au.