The Foreign Secretary will push for Mexico’s support for the UK to join an international trade pact as she visits the country on Thursday.
It comes after Mr Johnson conceded an agreement with the US was not about to be struck, following meetings with President Joe Biden.
But Ms Truss will focus on the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP), and discuss plans to develop a new and updated deal between the UK and Mexico.
The CPTPP is a free trade agreement between Australia, Brunei, Canada, Chile, Japan, Malaysia, Mexico, New Zealand, Peru, Singapore and Vietnam.
The UK applied to join in February, and in June the CPTPP announced that the accession process would begin.
Ms Truss said: “Closer ties with Mexico are a key part of our plan to strengthen economic, security and diplomatic links with like-minded allies who share our belief in free enterprise and free trade.
“A trade deal with Mexico, for example, will pave the way for us to join the CPTPP, one of the world’s biggest free trade areas.
“Our relationship with Mexico has huge potential. It could open vast new opportunities for businesses, support jobs across Britain, and help ensure we play a key role in an open and dynamic Indo-Pacific.”
Ms Truss will also formally open the new British Embassy building in Mexico City, after the previous one was damaged in the 2017 earthquake.
She will also attend a dinner with celebrity British-Mexican chef Fernando Stovell, who has held three Michelin stars and cooked for the Queen.