The public event in early May will be for the armchair sports fans who tuned in for the dulcet tones and quick wit that made Cometti a household name and footballers famous.
Cometti died in early March at the age of 76.
The "Western Australian legend" was lauded by WA Premier Roger Cook as one of the most respected voices in Australian sporting history.
"It is a privilege to hold a State Memorial Service in his honour and give Western Australians the opportunity to say goodbye," Premier Cook said on Sunday.
Born in Geraldton in 1949, Cometti's career spanned five decades.
Before becoming the voice of AFL, he played for and coached West Perth in the WAFL.
His broadcasting legacy includes calling the West Coast Eagles' first premiership in 1992, several Olympic Games, and iconic Test cricket matches.
Cometti joined Seven in 1986 and spent the better part of the next three decades at the network, also serving stints at Nine, 3AW and Triple M.
Along with long-time commentary partner Bruce McAvaney, he called some of the AFL's most memorable moments.
Cometti's contributions were widely recognised during his life, and his "Cometti-isms" such as 'Centimetre Perfect' have become part of football lore.
Beyond AFL, he was the voice of Kieren Perkins' 1500m gold and Susie O'Neill's triumphs at the Atlanta 1996 Games.
Cometti was appointed a Member of the Order of Australia (AM) in 2019 and inducted into both the Australian and Western Australian Football Halls of Fame.
In 2018, the Optus Stadium Media Centre was named in his honour, the stadium where he called his last call for the 2021 Grand Final.
Members of the public wishing to attend the May 4 farewell are asked to register via a state government website.
14°C