Australia's longest zipline has been approved for Brisbane, giving thrill-seekers the chance to speed through the treetops for 1,500 metres.

Construction on the zipline, along with a 1,400-metre "megazip" with six parallel lines, will begin at Mount Coot-tha, in Brisbane's west, in the new year and open in 2019, Brisbane Lord Mayor Graham Quirk said.

The line, to be built by Brisbane-based company Zipline Australia, will begin at the Mount Coot-tha summit and wind through the forest finishing at the JC Slaughter Falls picnic area.

Cr Quirk said the shorter 1,400 metre "megazip" would let adventurers ride side-by-side while taking in views of the Brisbane CBD at up to 65 kilometres per hour.

The megazip will start at the Mount Coot-tha lookout and finish at the Botanical Gardens at Toowong.

Map showing proposed zipline project on Mt Coot-tha in Brisbane. ( Supplied: Brisbane City Council )

Zipline Australia spokesman Matthew Thompson said the project would be the longest and highest vertical drop in the country.

"We're not looking to build the fastest zipline, we're looking to deliver an excellent experience that is safe and sympathetic to the environment," Mr Thompson said.

He said the technology being used would be previously unseen in Australia.

"This really takes it to another level," Mr Thompson said.

Cr Quirk said the Brisbane City Council would contribute $1 million to the project, which would also be funded through the private sector.

"The company will also construct the longest pedestrian suspended bridge walk in the Southern Hemisphere — a 300-metre walk through the treetops above JC Slaughter Falls," Cr Quirk said.

The technology being used for the project is previously unseen in Australia. ( Supplied: Brisbane City Council )

The project had been touted for several years and was promised by the Lord Mayor before his re-election in 2016.

The company has not decided on the cost per ride.

A shuttle bus will take patrons from the bottom of the ride back to the top.

Cr Quirk welcomed the tourism injection the zipline would create, but would not commit to a ride.

"I'm not a heights person — that's when the power of delegation comes into play," he said.

The council said there would be no need for a full environmental impact assessment but the surrounding environment would be treated "sensitively".