The One Nation leader has told parliament she will ignore a majority "yes" result of a postal survey on the issue.
Senator Hanson also slammed gay couples for trying to "take the word 'marriage'".
Senator Hanson warned marriage equality meant schoolchildren would be banned from calling their parents "mum and dad" so as not to offend the children of same-sex couples.
Earlier senior Labor figure Penny Wong delivered an impassioned speech urging the prime minister to protect children like her own.
"How do you think it feels for children in same-sex families ... to be told politely and courteously `Actually you're not quite normal, your families aren't as good'?" asked Senator Wong, who is a parent in a same-sex relationship.
Senator Wong lamented that those opposed to gay marriage were using "odd, bizarre and unconnected things" to make their argument.
