The Labor leader used his campaign launch to declare Labor would accept nothing less than equal rights.
Repeating his party's pledge to change the Marriage Act within 100 days of winning government, Mr Shorten declared no-one should have to justify his or her sexuality or love.
When Bill Shorten pushed his party's election pledge Putting People First at the Labor election launch on the weekend, one pledge he specified was marriage equality.
"We will provide the leadership in the parliament to deliver marriage equality within our first 100 days."
Hardening its stance against a public vote on same-sex marriage, Labor, with its strategic move, could doom the Government's plan for a plebiscite later this year.
"I do not want this plebiscite unleashing some of the homophobic attitudes which I think poison the debate about marriage equality, full stop. We all know this plebisicite is a tawdry, second-best option. Malcolm Turnbull never supported a plebiscite until he had to sell his political soul to the right wing of the Liberal Party to have this plebiscite."
Mr Shorten has described such a plebiscite as a taxpayer-funded platform for homophobia.
"In modern Australia, no-one should have to justify their sexuality or their love to anyone else. And instead of sitting in judgment, instead of providing a taxpayer-funded platform for homophobia, we will gift every Australian an equal right in respect of love, nothing less."
But Malcolm Turnbull is standing strong on his position to hold a plebiscite by the end of the year if re-elected.
"We have a very clear policy, which is that every Australian will get a vote on the subject. Everyone knows about that, and, of course, if we are successful on July the 2nd, then I have every expectation that the parliament will swiftly legislate for a plebiscite and a plebiscite will be held shortly after parliament resumes, which I would assume to be in August. So I would hope that a plebiscite could be held before the end of the year."
Education Minister Simon Birmingham has told Sky News Mr Shorten needs to moderate his language.
He says he has faith Australians will conduct a sensible, measured debate.
"Ultimately, having done that, we will have a more unifying outcome from that plebiscite in regards to marriage equality. You well know my views on this issue -- they've been on the public record for a very long period of time now, and I will be voting yes. Malcolm Turnbull said that he will be voting yes. We will, of course, urge every single Australian, whatever their position, to adopt careful, moderate language ... argue the merits of the case, indeed, but respect the positions of their opponents."
However, Greens leader Richard Di Natale says the public vote would unleash a negative reaction.
"We need to recognise that a plebiscite will unleash those voices of hate in the community. It will do that. And we give those views legitimacy by endorsing a plebiscite, and that's the reason that we shouldn't have one."
Labor Senate leader Penny Wong says the Prime Minister has caved in to the Coalition and given up his original stance on a plebiscite.
"A plebiscite was proposed not because the Liberal Party decided that they wanted to progress this issue. A plebiscite was proposed because the Liberal Party decided they couldn't progress this issue, because members of the hard right of the Liberal Party were too angry about it. And Malcolm Turnbull tapped the mat.* After saying to everybody he didn't support a plebiscite, he's tapped the mat and given in to (Eric) Abetz, (Cory) Bernardi and (George) Christensen. That is what has happened."
Ms Wong, who has two children with partner Sophie Allouache, says if marriage equality is a priority for Australians, vote Labor.
The issue of a public vote initially flared up at the third election debate last week, when the question of same-sex marriage was put to both leaders.
Mr Shorten initially suggested the same level of hate could come out of a plebiscite campaign as the Orlando massacre and said LGBTI families should not be subjected to hate.
Mr Turnbull hit back, saying Australia can have a civil and respectful conversation and make a decision as a nation.