Brian Burston was a One Nation senator at 9.30am, an independent at 10am, and Clive Palmer's first recruit to his United Australia Party at 10.30am.
The senator checked his watch as he said he only made the decision to join the new party after telling the Senate he was an independent.
Mr Palmer flew into Canberra for the announcement of Senator Burston's move, which was flagged to media hours earlier.
"We will unite Australia and we will bring integrity back into the Senate," the NSW senator told reporters in Canberra on Monday.
Asked whether he had lied to parliament, Senator Burston claimed he'd only made the decision to join the rebadged party after - not before - telling the Senate he was an independent.
"I am very happy to say that Brian has shown a great amount of courage and a great amount of foresight to stand up for the people who elected him, to aim for their aspirations," Mr Palmer told reporters.
"I look forward to a long and happy relationship with him."
In a chaotic press conference, Labor MP Cathy O'Toole heckled Mr Palmer about former Queensland Nickel workers who say he still hasn't paid their entitlements.
Mr Palmer blamed the liquidators for any missing money, and said he planned to reopen his Townsville nickel refinery.
He railed against the media and reporters, while also telling journalists to read about stories about how wealthy he is.
The grilling was cut short when the sprinklers at Parliament House came on.
Mr Palmer later confirmed he was interested in running for the north Queensland seat of Herbert, which Ms O'Toole won in 2016.
He previously held the seat of Fairfax from 2013 to 2016.
Prime Minister Malcolm Turnbull did not comment on Senator Burston's defection.
"As far as Mr Palmer is concerned, I guess all I can say is we have seen that film before," Mr Turnbull told reporters.
Labor senator Murray Watt said Senator Burston would be joining "another circus" with Mr Palmer.
"His name is mud in Townsville and in much of Queensland because of the way that he has run his businesses into the ground and ripped off working people," Senator Watt told reporters.
Former Liberal prime minister Tony Abbott said voters were sick of people like Mr Palmer.
"He's driven every business that he's ever run into the ground," he told Sydney radio 2GB.
"The last thing we need are more spivs in the parliament."
One Nation leader senator Pauline Hanson now has only one parliamentary party colleague - Western Australia senator Peter Georgiou.