Independent Steve Martin and Liberal Richard Colbeck have been sworn in to the Senate.
Tasmania has two new senators with former tourism minister Richard Colbeck and Jacqui Lambie's replacement Steve Martin sworn in to parliament.
Senator Colbeck fills the vacancy created by former Senate president Stephen Parry's resignation over the citizenship fiasco, which also ensnared Ms Lambie.
"Welcome back, Lazarus," Nationals senator John Williams said as he shook Senator Colbeck's hand in parliament on Monday.
Senator Colbeck's political re-birth comes after he was relegated down the Liberals' Tasmanian Senate ticket for the 2016 election and failed to retain his spot in the upper house despite garnering more than 13,000 below-the-line votes.
He was first elected to parliament in 2002.
Senator Martin, who is the Devonport mayor, last week fell out with Ms Lambie after he refused to step aside and clear the way for her return to parliament.
In a letter released to media on Wednesday, Ms Lambie said Senator Martin had broken the values of "mateship, respect and integrity" by terminating staff members he said he would retain.
The High Court ruled on Friday he was eligible to replace Ms Lambie because being a local government councillor did not constitute an "office of profit under the Crown".