Trade Minister Tim Groser says Mexico joining the Trans-Pacific Partnership (TPP) is a "shot in the arm" for the contentious free trade agreement.
On Monday night it was announced Mexico would join the agreement, which is being thrashed out by nine Pacific Rim countries, including New Zealand, the United States and Australia, to set up what could become one of the world's largest free-trade zones.
"Today's announcement is a shot in the arm for the TPP, which underscores the importance of the opportunity this negotiation creates. It takes us another step closer to that regional goal," Mr Groser said on Tuesday.
The move to join showed there was a groundswell of momentum behind the TPP, he said.
Mexico will need to complete any applicable domestic legal procedures, which could take weeks or months, Mr Groser said.
Canada has expressed an interest in joining the TPP, while Japan is keeping a close eye on its development.
Opponents of the TPP say that if New Zealand signs up it will allow foreign companies to sue the government over things like tobacco control and oil drilling rules.
The TPP countries have completed 12 rounds of negotiations and the next round is scheduled for July 2-10, in San Diego.