Left-wing parties and the People-Animals-Nature party voted in favour and the opposition Social Democrats and the conservative CDS-People’s Party abstained.
The socialist member of parliament Carla Tavares defended that the number one priority since the beginning of Brexit were the citizens and their rights.
"Our community in the UK - where around 400,000 people reside - employees and students - need guarantees that their rights will be assured following Brexit," Tavares said during the presentation of the motion, which was put forward by the Socialist party.
"Portugal has already shown it is available to guarantee all the rights of British citizens residing in Portugal, so reciprocal protection of rights should be our main priority, hand in hand with facilitating mobility for temporary stays," she added.
Following her intervention, Pedro Filipe Soares, the Left Bloc's parliamentary leader, called the diploma "innocuous" and "late," saying an initiative for an identical recommendation of measures had already been taken by the parliament.
The UK's departure date had originally been set for March 29, but amid requests to resign, prime minister Theresa May recently agreed with Brussels to extend the date of its departure from the European Union until October 31.