They said the decision, announced at a news conference at the Swiss headquarters of UEFA, had the full support of European football’s governing body and also of the Spanish, Portuguese and Ukrainian governments.
The original proposal was made public two years ago but has been given a political impetus by Russia’s invasion of Ukraine.
“The institutional headquarters are in Madrid, the administrative headquarters are in Lisbon. Now the Ukrainian delegation will unite with us,” RFEF president Luis Rubiales said.
“Our bid is not an Iberian bid anymore, it’s a European bid. I’m convinced that now our bid is much better than before. Football is universal and if it is capable of changing the life of people in so many ways it should also be used for doing good.
“In the coming months, we will come to work on practicalities,” he added.
The Spain, Portugal and Ukraine bid for the 2030 tournament will compete against other candidacies such as a collaboration between Egypt, Greece and Saudi Arabia, and a joint South American proposal from Uruguay, Argentina, Paraguay and Chile.
“We are convinced that by 2030 we will have peace in Europe and that Ukraine will be able to host it (the tournament) in the best way possible,” said FPF president Fernando Soares Gomes da Silva.
The head of Ukraine’s football federation, Andriy Pavelko, also attended Wednesday’s news conference.
Russian forces invaded Ukraine on Feb 24 in the largest military operation seen in Europe since World War Two.
Tens of thousands of people have been killed during seven months of fighting, millions have fled and cities and towns have been reduced to rubble.
Moscow calls its action a “special military operation” to disarm and “denazify” Ukraine, while Kyiv and its Western allies say it is an illegal land grab.
RFEF, which organised the 1982 edition, said in a statement the idea was backed by UEFA president Aleksander Ceferin.
“The Royal Spanish Football Federation and the Portuguese Football Federation (FPF) have incorporated the Ukrainian Football Association (UAF) into the Iberian Bid to organise the 2030 World Cup,” RFEF said.
“With the full support of Aleksander Ceferin, the Iberian bid incorporates the federation chaired by Andriy Pavelko in order to build bridges and project a message of unity, solidarity and generosity from all of European football.
“The candidacy strengthens ties with Europe by generating hope and providing reconstruction tools to the Ukrainian people, who have expressed their pride and gratitude for participating in this project.”
Portugal held the 2004 European Championship while Ukraine was a joint host with Poland of Euro 2012.
“The example of tenacity and resilience set by the Ukrainian people is inspiring,” the FPF said.
The FPF added that the joint bid “aims to contribute through the power of football to the recovery of a country undergoing reconstruction”.
It added the terms of Ukraine’s role in the bid “will be discussed and defined in due course”.
The 2026 edition has already been awarded to three countries — Canada, Mexico and the United States.
More than half of the 21 World Cup finals already staged have been in Europe but later this year Qatar will host the finals, the first time they have been played in the Middle East.