Bruce Woodley said the Conservative Political Action Conference (CPAC) featured I Am Australian without approval while the song's co-author revealed Senator Hanson had been previously threatened with legal action over its potential use.
I Am Australian was sung as part of CPAC's opening ceremony in Brisbane on Saturday, after renditions of the national anthem and Waltzing Matilda.
The song - originally co-written by Woodley and the Bushwackers' Dobe Newton in 1987 - was also advertised as part of the official conference program agenda.
Woodley and Newton lambasted CPAC organisers, saying the iconic song about unity in diversity was at odds with the anti-immigration views expressed at the conference.
"No permission was either sought or given by me for the use of my song," Woodley told AAP on Monday.
The song's theme is encapsulated in its line: "we are one, but we are many, and from all the lands of earth we come".
After the song's performance, speakers including Senator Hanson and opposition leader Angus Taylor condemned what they called "mass immigration".
"I would absolutely never endorse the use of the song associated with those purposes," Newton said.
He said when Senator Hanson tried to use the song in a previous election campaign, he and Woodley threatened her with legal action.
"We said to each other 'what planet is she on'?" Newton said.
"Bruce and I got a friend of ours to write a furious solicitor's letter threatening to sue her, and she actually changed her mind."
He said that during the 2023 Voice to Parliament referendum, both the Yes and No campaigns approached he and Woodley to use the song.
Both were denied.
Mark Callaghan, leader of the band Ganggajang and a long-serving board member of copyright management organisations APRA-AMCOS, said CPAC's unauthorised use of the song was illegal.
"The bottom line is permission must be sought and approved for any public performance, especially in that political context," he told AAP.
However, he said enforcement was "like playing whack-a-mole", with his song Sounds of Then (This is Australia) frequently misused for commercial and political purposes without permission.
"We are finding it's a real problem all over the internet because people put up political posts and then add Sounds of Then, or I Am Australian or (Icehouse's) Great Southern Land and implying some sort of connection."
CPAC organisers have been contacted for comment.
The 1997 recording of I Am Australian by late Seekers singer Judith Durham, Air Supply's Russell Hitchcock and Yothu Yindi leader, the late Dr M Yunupingu, has become an Australian standard, added to the National Film and Sound Archive registry in 2023.
It was used with permission by the Australian Republican Movement in radio and television advertisements during the 1999 referendum.
It is also regularly used in major national and sporting events.
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