Aoife (36), the sister of UFC fighter Conor McGregor, paid a 'physical visit' to Portlaoise Prison to visit with Whelan two weeks ago.
The 39-year-old, a key garda target over the past three decades due to his involvement in organised crime, was banged up for 18 months on November 15 for money laundering. Aoife has no involvement in criminality and is a respected businesswoman.
Aoife's was the first physical visit he has received since being locked up.
Due to Covid, inmates are only allowed one physical visit and one video visit per fortnight.
The pair are understood to have become close friends after Aoife's marriage to husband Mark Elliot broke down in November last year.
Father-of-four Whelan lost his own partner in tragic circumstances in 2020.
Elliot, who served three years for possession of €40,000 worth of cannabis, confirmed to the
Sunday World in August that his relationship with Aoife had broken down as he did not wish to have more children.
"It was basically to do with kids - she wanted a baby and I didn't," said Mark (45) who has twin 20-year-old daughters from a previous relationship.
Sunday World contacted Aoife for comment through her Instagram account on Thursday, however no response to our request had been received at the time of going to print.
Whelan is also friends with Conor McGregor and a member of his Black Forge pub football team.
But The Wig's pub football days were put on hold by the Special Criminal Court in November after it heard how he drunkenly boasted to gardai that he got the €1,200 in cash from "up his Swiss roll" during an arrest at the Intercontinental Hotel, Ballsbridge, Dublin on January 31, 2019.
He also told detectives "I'm a dangerous criminal" and to "look me up".
The court heard this was a reference to Whelan being jailed for six years over a €1.6m drug seizure at a hotel in Dublin's city centre.
The infamous bust, carried out at the Holiday Inn when Whelan was just 17, was seen as the beginning of the Crumlin/Drimnagh feud which led to 16 people being murdered.
On being caught, he told gardai he could do 10 years in jail "standing on his head."
Arising from his arrest at the Intercontinental, Whelan pleaded guilty to participating in the actions of an organised crime gang by laundering money for the group.
He also admitted to being in possession of €1,200 in cash and a €28,000 Audemars Piguet Royal Oak gentleman's watch, both of which were found to be the proceeds of crime.
The Special Criminal Court heard Whelan had 33 previous convictions including the prison term served for the €1.6m drug seizure, as well as for violent disorder, criminal damage and assault causing harm.
He also has a conviction for grievous bodily harm over a Spanish bar brawl involving two other people in 2016, for which he received a two-year suspended sentence.
Defence counsel Michael Bowman said Whelan had four children, aged between three and 10, and that he was their primary carer following the death of his partner.
Mr Bowman said Whelan had undergone drug and alcohol counselling and that his client's priority was the upbringing of his children since the passing of his partner.
Counsel said that Whelan had "grasped" the opportunity to be part of a "social contract for the betterment of his family" and that supporting documents showed that he was "genuine" in his efforts.
After hearing that Whelan's partner died by suicide, Mr Justice Tony Hunt said it took "an enormous personal tragedy to bring about a change in his lifestyle".
The judge said money laundering was an essential component of a wide range of criminal activity and that, while Whelan is a father-of-four children and that the court must have regard to what effect a custodial sentence would have on them, this is not a reason in itself not to imprison him.
Mr Justice Hunt sentenced Whelan to three years imprisonment on each count, to run concurrently, and suspended the last 18 months of each sentence.
This, he said, would be suspended for four years so the defendant could demonstrate his change in lifestyle on a longer term.