Dimitrov and Hewitt join a line-up that already includes Boris Becker (Germany), Marat Safin (Russia); as well as Tim Henman (Great Britain).
Hewitt will lead Australia's team of Alex de Minaur and Nick Kyrgios in Brisbane in the brand new event which takes place in three cities in Australia from 3-12 January 2020.
Becker's team includes Alexander Zverev; while Safin will spearhead a team including Daniil Medvedev and Karen Khachanov.
BRISBANE (GROUP A)
Serbia Nenad Zimonjic
France Gilles Simon
South Africa Jeff Coetzee
Chile Paul Capdeville
BRISBANE (GROUP F)
Germany Boris Becker
Greece Apostolos Tsitsipas
Canada Adriano Fuorivia
Australia Lleyton Hewitt
PERTH (GROUP B)
Spain Francisco Roig
Japan Satoshi Yabushi
Georgia David Kvernadze
Uruguay Felipe Maccio
PERTH (GROUP D)
Russia Marat Safin
Italy Vincenzo Santopadre
USA David Macpherson
Norway Christian Ruud
SYDNEY (GROUP C)
Belgium Steve Darcis
Great Britain Tim Henman
Bulgaria Grigor Dimitrov
Moldova Vladimir Albot
SYDNEY (GROUP E)
Austria Thomas Muster
Croatia Luka Kutanjac
Argentina Gaston Gaudio
Poland Marcin Matkowski