The original proposal was made public two years ago and the Spanish football association (RFEF) 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 in a statement.
“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,” it added.
Portugal hosted 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 that the terms of Ukraine’s role in the bid “will be discussed and defined in due course”.
It follows the announcement last month from an Egyptian official that Egypt, Greece and Saudi Arabia are in talks to jointly host the 2030 World Cup.
In August, Uruguay, Argentina, Chile and Paraguay launched their bid to host the event — which is the centenary of the first World Cup, held in Uruguay — with the hope of bringing the global showpiece back to its first home.
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.