Mr Robert was assistant treasurer but has been promoted to cabinet as Government Services Minister and will oversee the National Disability Insurance Scheme.
Mr Hawke will be International Development Minister and assistant Defence Minister, in a bid to build stronger defence and economic ties with the Pacific.
Both men were key supporters of Mr Morrison in the leadership contest in August.
Michael Sukkar, who quit a previous role in August in a bid to get Peter Dutton into the top job, has been brought in from the cold as assistant treasurer to oversee the first home loan deposit scheme.
Nationals MP David Littleproud has been given water resources, natural disasters, and emergency management, while Bridget McKenzie will become Australia’s first female Agriculture Minister.
Alan Tudge will be Population Minister, while Richard Colbeck will take Aged Care, Youth and Sport.
Victorian senator Mitch Fifield will quit the Senate and go to the United Nations as ambassador, after asking to leave. “I would have been very happy for Mitch to continue to serve in communications and the arts,” Mr Morrison said.
NSW senator Arthur Sinodinos will replace Joe Hockey as ambassador to the United States.
Linda Reynolds will be Defence Minister, Peter Dutton will remain in Home Affairs and Dan Tehan will stay in Education.
Josh Frydenberg remains Treasurer, while Mathias Cormann stays on as Finance Minister.
Mr Morrison was given room to promote and reshuffle his ministry after a number of high-profile ministers retired at the election.