Frank Zumbo pressured the women, who were looking to further their careers, into "kisses and cuddles", touching them inappropriately and exposing himself to one victim.
He was convicted in February of sex crimes occurring at various locations across Sydney from 2014 to 2018.
The 56-year-old drew the women into a "world of his own design", where he was the director of everything, prosecutors told a hearing in Sydney's Downing Centre local court on Tuesday.
The four victims were aged between 19 and 24 at the time of the offending, while Zumbo was more than twice their ages.
As an aide to Mr Kelly, the then-Liberal MP for the southern Sydney seat of Hughes, Zumbo was responsible for hiring staff to work in his electoral office.
"Really at the heart of these offences is the notion of power," crown prosecutor Shaun Croner told the court.
"The powerful and the powerless."
Zumbo presented himself to the women as a person of significant power and influence in the political sphere, the court was told.
"They needed that leg up in their career," Mr Croner said.
Multiple complainants said the former aide would greet them with hugs and kisses in the office, conduct that escalated to groping their breasts or touching their backsides.
"There was an introduction of touch in an innocuous way that was designed, in the Crowns' submission, to break down barriers," Mr Croner said.
"All of these victims said they did not want a kiss and hug, they did not want what was described as a 'social greeting'."
One woman said Zumbo exposed his penis to her while they were on a park bench, while another said he touched her vagina while they were in his car by the roadside.
Magistrate Gareth Christofi earlier acquitted Zumbo of two further charges of aggravated sexual touching relating to a fifth complainant, the woman who first went to police and sparked a criminal investigation.
Mr Christofi said he could not be satisfied beyond a reasonable doubt that Zumbo's touching of the teenager's thigh and rubbing of her shoulder was sexual.
Zumbo's lawyer Carolyn Davenport argued he had contributed to society through his work in politics and academia and should be entitled to some leniency.
The case is expected to return to court for sentence on April 12.
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