Bult said the "absolute priority" was to contact the players and "get on with the job now that the decision has been made".
Marshall has been coaching at Three Kings for the past few seasons in the Northern Regional Premier League but has relinquished that role in signing a 12-month contract at Waitakere United.
"I applied for the same job a few years back but Neil Emblen got the nod," said Marshall. "My first step will be to talk with the players, something I plan to do in the next two days.
"Apart from Chris Bale, who has gone to Auckland City, I hope that most of last season's squad are still available and want to play for the club," he said. "This is a more senior role than any of my previous coaching. It is exactly where I want to be at this stage of my career."
The season kicks off with the Charity Cup clash with old rivals Auckland City at Fred Taylor Park on October 28.
PAUL MARSHALL
Born: October 14, 1962, Auckland.
Secondary School: Onehunga High.
Clubs: Mt Albert Ponsonby, Metro, Manurewa, Gisborne City, Papatoetoe.
Coaching: Three Kings United, Mt Albert Grammar (girls).