Adshel is encouraging its clients and business partners to hand over $700,000 of outdoor advertising space for three charities, using a Facebook app.
The competition, now in its fourth year, will ask people to vote for which of R U OK Day, Open Families Australia and Royal Institute for Deaf and Blind Children they would like to support.
The winner will be given $400,000 worth of ad space, with the other two $200,000 and $100,000 each respectively.
Nicole McInnes, director of marketing at Adshel said: “We take our commitment to the community very seriously. There are so many not-for-profit organisations doing great work who struggle to be heard.
“It is our hope that by providing free access to our out-of- home assets, we will help charities gather support from the public.”
Last year’s competition winner was the RSPCA and so far this year Adshel has given more than $1m of ad space away to a host of charities.
Voting closes on December 24 and can be seen here.