Controversial former MP Hanson had planned to sell her million dollar home in rural Queensland and move to Britain.
But she sparked outrage when she told commercial TV she would not take offers from non-resident Asians, or Muslims because she thought they would cause "problems" for the country.
Estate agent Keith Edwards said he had received a torrent of threatening phone calls and emails in the wake of Ms Hanson's remarks.
"I've received an inordinate amount of threatening phone calls and emails," Edwards said.
Controversial figure
"It's been horrendous. I've had about four hours' sleep in three days and I'm worn out. I'm absolutely at the end of my tether."
Earlier this week Hanson, who had a brief and controversial stint in the national parliament in the 1990s, said: "I don't believe that they (Muslims) are compatible with our way of life, our culture.
"And I think we are going to have problems with them in this country further down the track, so I have no intention of selling my home to a Muslim."
She later apologised to the estate agent but did not retract her original comments.
"If I've upset Keith and his business, LJ Hooker, I didn't mean to do that," Hanson told Network Ten TV.
"(But) if someone turns up to my doorstep that I'm not happy with I won't allow them through my house."
Agent caught in TV sting
Edwards said his business was suffering after he was caught in a TV sting passing on Hanson's instructions to an Asian couple and two Muslims posing as potential buyers.
"The phone calls, the emails, the effect on my business already. It's a new franchise, I'm doing everything I can to stay open in hard times," he said.
"I'm already receiving cancellations of business. It's seriously affecting my entire life. In three days, everything's changed."
Hanson sparked international condemnation in 1996 when she said Australia was in danger of being "swamped by Asians" in her maiden parliamentary speech, before losing her seat two years later.
She spent several months in jail in 2003 for fraudulently spending electoral funds before the judgement was overturned.
In February she announced she was leaving Australia "indefinitely" after becoming disillusioned with the country.
