A 25ft-high red squirrel bridge will be built over a busy road in a bid to stop the animals being run over.
National Trust plans for the rope bridge over the A4080 at Llanfairpwll have been approved by Anglesey council.
The charity said tens of red squirrels were run over each year and this was part of efforts to boost its numbers.
Iwan Ellis-Roberts of the National Trust said: "We're overjoyed plans have gone through. It helps them to populate other areas."
In 2008, six red squirrels were released into the gardens at Plas Newydd and they now number more than 100.
The bridge will link the grounds of the 18th Century mansion to neighbouring woodland and conservationists hope this will encourage the animals to safely scamper to new habitats.
Holly Peek, a Red Squirrels Trust Wales ranger, said: "Red squirrels much prefer being in the canopy - they don't like being on the floor - so it's hoped if we provide that option over crossing the road, they will take it.
"If there's more squirrels around, the population is going to grow and they will spread to new areas as well."
It is part of a £10,000 plan that also includes a new squirrel hide and nest boxes. The National Trust is in the process of raising the cash and hopes the bridge will be ready for the autumn.
Mr Ellis-Roberts said the bridge brought some risks as red squirrels could come into contact with greys, which can carry a pox that is deadly to their native counterparts.
Although Anglesey is considered grey squirrel-free, Mr Ellis-Roberts said there had been sightings of the animal and it is thought they may have swum over from the mainland or crossed the bridge.
There are plans to install camera traps on the bridge so its effectiveness can be monitored.