Thousands have rallied in Boorloo/Perth to express solidarity for the mass Māori-led march in Aotearoa to defend the Treaty of Waitangi.

The hikoi mo te Tiriti began in the far north of Aotearoa's north island ten days ago in defiance of the Treaty Principles Bill, which seeks to weaken the Treaty of Waitangi. The mass movement reached Wellington this week, with at least 50,000 people gathering in the capital on Tuesday.

The Treaty of Waitangi was signed in 1840 between the British Crown and more than 540 Māori rangatira (chiefs). Certain laws and regulations in place in Aotearoa have been enacted over the years to reflect the principles of the Treaty, including Māori representation in decision-making.

The Treaty Principles Bill introduced by the ACT party, a coalition partner in the conservative government, aims to "reinterpret" the Treaty. While supporters claim it aims for "equality", critics note it would reduce Māori rights.

Speaking to the huge crowd in Boorloo on Wednesday, Noongar activist Megan Krakouer sent a message to the hikoi.

"Your struggle is our struggle. We see you, we stand with you, and we will not stop until justice is won," she said.

"Together across nations and oceans, we are stronger than the systems that seek to divide us."

Ms Krakouer said Indigenous peoples on both sides of the Tasman Sea are united by many things.

"Resistance does, resilience does, and justice will," she said.

"We see here in this country, the decimation, the ruining of First Nations people's lives, it is absolutely horrendous.

"It is not rocket science to work out what is happening to our brothers and sisters on the other side of the world. What is proposed is wrong. Continue to fight, continue to make your voices rise, and it can be defeated."