Scott leaves the role to look at other opportunities; he was hired permanently in August 2017, which came after six months of service as interim Australia CEO.
Shannon was already a Non-executive Director and consultant to GVC in Australia following its acquisition of Neds International.
Previously, Shannon was Executive Chairman of Neds and served as CEO of Ladbrokes Australia between 2013 and 2017.
His new role will involve leading both the Ladbrokes Australia and Neds brands.
GVC CEO Kenny Alexander said: "We are delighted to announce Dean’s appointment. He is a highly dynamic, experienced leader with the entrepreneurial skills that will drive our Australian business to even greater success in the future.
"I’d also like to put on record my thanks to Jason Scott for the job he has done in establishing the group as a market leader in Australia."
Shannon said: "I am truly excited to be leading GVC’s Australian businesses. I believe in Ladbrokes and Neds we have two of the leading brands in the market and, backed by our proprietary technology and highly talented team, we are very well placed for growth."
