Rod Culleton, late on Sunday night, announced he would stay in parliament as an independent after claiming he was the victim of "un-Australian" behaviour by party colleagues and citing policy splits.
Tensions are so fraught between the pair, that Senator Hanson only found out about Senator Culleton's resignation on social media, she said.
"He hasn't even rung me," she told the Nine Network on Monday.
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Culleton quits One Nation, slams 'un-Australian behaviour'
Earlier the One Nation leader said she was glad to see the back of the West Australian senator, whose eligibilty to contest the July 2 election is subject to a High Court ruling.
"Rod was a pain in my backside," she told the Seven Network.
In his late-night statement, Senator Culleton said policy decisions were run in morning media with no consultation or agreement from the party room.
But Senator Hanson said he hardly ever turned up to morning meetings with the One Nation team and advisors to decide policy positions.
"He was too busy running around the place doing his own media, or actually going to other meetings and dealing with his legal proceedings," she said.
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'Gone to his head': Hanson says she can't work with Culleton
Senator Hanson revealed she said "yes" when Senator Culleton asked her if she wanted him to resign after he requested money to fight the High Court challenge.
Senator Hanson doubted Senator Culleton would acknowledge he was elected under the One Nation banner.
"He is ego driven and he loves the media," she said.
"It is a shame this has happened. I am sorry to the people. I did not expect him to be this type of man."
Fellow crossbencher Derryn Hinch questioned whether Senator Hanson would parachute her chief-of-staff James Ashby into the WA Senate seat, should the High Court rule Senator Culleton's election invalid.
She rejected the claim as absolute rubbish, insisting the staffer was not interested.
Asked what Senator Culleton's resignation meant for government negotiations with the crossbench, Treasurer Scott Morrison said it would wait to see the Senate composition when parliament resumed in February.
Government backbencher Eric Abetz, who managed Senate business under Tony Abbott, says it's likely Senator Culleton's resignation will make the coalition's task harder.
Police arrest two men at Rod Culleton hearing
Senator Rod Culleton's bankruptcy hearing has taken another bizarre turn with two West Australian police officers and a federal police officer turning up to arrest two people at the Federal Court in Perth.
Senator Culleton had objected to the two men, farmers and former friends Bruce Bell and Frank Bertola, being in the court because he had violence restraining orders against them.
A furious Mr Bell launched a long verbal tirade against the police, accusing them of unlawful arrest and corruption.
It comes after Senator Rodney Culleton stormed out of a Federal Court hearing over a broken land deal debt in the latest bizarre episode for the WA farmer.
He complained that two men were present in court against whom his wife has taken out violence restraining orders.
The two men, farmers Bruce Bell and Frank Bertola, once fought the banks alongside Senator Culleton but are now trying to challenge his eligibility as an MP.
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