Aeromexico will begin Barcelona service on 15 June, after Emirates dropped plans to serve Mexico City from Barcelona following protests from the Mexican carrier.
Aeromexico will operate thrice weekly from Mexico City to Barcelona with Boeing 787-8 aircraft.
Barcelona will be the airline's fifth European destination after Amsterdam, London, Paris and Madrid.
The SkyTeam carrier had previously announced plans to return to Barcelona in November 2018, after having previously served the Spanish city between 2007 and 2012.
But it later suspended plans for the flights, blaming Emirates for the decision in May 2018. Emirates had been awarded rights to serve Mexico City via a stop in Barcelona from its hub in Dubai. Echoing statements of its US partner and shareholder Delta Air Lines, Aeromexico had said that Emirates benefits from government subsidies.
Subsequently, Emirates said in September 2018 that it will no longer serve Mexico City, after Mexican authorities informed the Gulf carrier that it could operate only thrice weekly instead of daily.
"Despite previous assurances that slots [at Mexico City airport] were not an issue at the flight timings requested, the Mexican authorities have informed us that we will not be able to operate daily services, but only three flights a week," said Emirates at that time, calling the move "hugely disappointing".
No airline flies nonstop between Mexico City and Barcelona, FlightGlobal schedules data show.
Separately, Aeromexico plans to increase frequencies on its routes to Madrid and Paris later this year, growing to up to 18 weekly and 11 weekly flights respectively, it says. The airline currently serves Madrid 10 times weekly and Paris nine times weekly, respectively.
The Mexican carrier competes against Iberia on the Madrid service and Air France on the Paris route.