Mateusz Morawiecki made the comments after referencing the “blooming” Polish economy during a press conference following bilateral talks at Lancaster House.
Mrs May said the UK was committed to protecting the rights of European Union citizens living in the UK if Britain crashes out of the EU without a deal.
She said: “My message to Polish people is clear. You can stay, and we want you to stay.”
The Prime Minister repeated the message in Polish, before adding: “As we leave the EU, the relationship with our closest partners like Poland remains vital.
“I have reiterated to Prime Minister Morawiecki that Britain will continue to work with Poland and other member states to protect our people, shared values and interests.”
Mr Morawiecki welcomed the comments, before encouraging Poles to consider returning to Poland.
He said: “Thank you very much once again and I’m very happy about something you mentioned during your speech - our Polish diaspora here in the United Kingdom, Polish citizens who live in the UK can feel safe, can be sure that their rights and social rights included will be respected.
“This was very important for our government as this is our responsibility to make sure that our citizens - Poles who left countries and found their second home in the UK - have their rights respected.
“We are happy about the fact that they found a new home, however, as our economy is blooming, we would like to encourage our citizens to consider returning to Poland, although we respect everyone’s personal choices.”
Mr Morawiecki earlier said Mrs May’s Brexit deal was “the best that could have been obtained”.
He told the press conference: “We believe the current Withdrawal Agreement is the best that could be obtained.
“It’s a window towards the future and based on the Withdrawal Agreement we shall be able to work out detailed trade relations under the new circumstances and also co-operation in the realm of international policy, security and all those areas of the utmost importance to us.
“This agreement should come into force, it would be beneficial for both parties and after March 2019 it will allow us to build solid, close relations between not only our respective countries but the UK and the EU.”