"If he's competitive, he will lift our A-League profile", Rallis said.
A season-long deal could follow if it goes well, he told commercial broadcaster Channel Seven.
Since retiring from athletics, the Jamaican has trained with Borussia Dortmund and most recently linked up with Norwegian side Strømsgodset.
The eight-time Olympic gold medallist is now negotiating with the New South Wales club to take part in a six-week trial that could potentially see him signed for a full season, Mariners chief executive Shaun Mielekamp said.
Rallis is now in the United Kingdom and has been dealing directly with Bolt's representative Ricky Simms, who he says is fully supportive of the idea.
Australian football agent Tony Rallis said Monday a "deal between the Mariners and Usain Bolt in principle has been agreed, subject to a couple of benchmarks".
"Mainly, a trial, and of course marquee funds support from the FFA".
No contract is guaranteed for Bolt, who retired from the track after the 2017 World Championships and has previously expressed a desire to play professional football.
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"This bloke's an ambitious athlete".
The fastest man in history has joined Central Coast Mariners, in Australia's top league.
Mielekamp said Bolt's signing has been in the works for four or five months.
His trial would be similar to the one Jarryd Hayne underwent before earning a contract to play American Football.
Though on the pitch for less than half an hour, Bolt struggled with his first touch and, playing as a forward, failed to make the runs you'd expect of the sprint king.
Mielekamp said reports of Bolt's performance at the European clubs he has trialled with have been "pretty good", and that "every time he trains, he improves significantly".
"Because if he comes and he's not up to the level then it actually has a detrimental effect".
"He's got a very good left foot and only time will tell what level he's at, and does that fit the A-League", he added.