And then it was done. Spontaneous applause broke out in a brief moment of celebration, a recognition from the gathered delegates that the signing - ceremonial though it was - represented a major milestone after five years of intense negotiation.
Skeptics will say the hard part is really just beginning as respective governments need to pass the partnership into law before it can be ratified.
Passage through the US Congress is clearly the biggest hurdle with failure there threatening the viability of the deal.
But US Trade Representative Michael Froman was unfazed by suggestions that American politics could be a road block.
He argued that the hard sell on Congress was only just beginning and he was "confident" that the members would eventually see the benefits.
For many of the trade ministers it seems that the focus is already moving towards expansion of the deal and the inclusion of more nations.
Certainly they expressed a great sense of optimism that the initial projections for economic gain are just the beginning as the partnership opens new opportunities for trade.
Malaysia's Minister of International Trade and Industry, Mustapa Mohamed, said that the debate in his country has produced no shortage of critics with studies and projections downplaying the economic gains.
But you either listened to those who produced studies based on models and assumptions, he said. Or you listened to those on the ground doing business.
"For us in Malaysia we've been talking to people in industry and businesses and we know they are looking forward to it."
Others, such as Peru's Magali Silva, were keen to emphasis that the partnership represented much more than just the removal of tariffs.
The TPP was an agreement that had thought about SME's (small and medium enterprise), she said.
SME's get their own section in the TPP document with specific commitments required from each signatory to promote opportunities for small players to trade across the region.
Trade ministers were also keen to emphasise the level playing field the TPP would create for trade in the region.
Australia's Andrew Robb talked about untangling the "noodle bowl" of regulations across the region. This is the part of the deal is gets people most excited.
For the signatories it is about fairness for traders and businesses and the right to do business across the region with some certainty about trade rules.
New Zealand trade advocates like the NZ International Business Forum's Stephen Jacobi have argued that New Zealand as a small trading nation will be a net beneficiary of moves towards more uniform regional rules.
But those outside in the streets yesterday clearly see this as corporate play to undermine national sovereignty.
It's unlikely that the optimism in evidence at the signing yesterday would sway many of the protesters. But it was heartening to see it very much in evidence from such a large and diverse group of nations.
