"We are united in our total condemnation of terrorism and our commitment to stamp out this evil", May said ahead of her visit.
In a meeting lasting around 90 minutes, the Prime Minister updated her top team on the on-going discussions with the Unionists to secure an agreement propping up the Tory minority government.
"The parliamentary arithmetic is such that we are going to have to work with everyone", he said.
Arlene Foster says she hopes to conclude the talks soon.
The so-called "confidence and supply" government being discussed by the Conservatives and the DUP has sparked widespread criticism due to several controversial views held by the latter on homosexuality and climate change.
The Northern Ireland party has come to May's aid after last week's general election left the prime minister eight seats short of the 326 seats needed in the House of Commons to command an overall majority. But an alliance between May and a pro-Union party like the DUP could undermine the confidence of Northern Ireland's Catholics in the process and revive tensions in an area bordering the EU.
May is under pressure to take on a more cross-party approach to Brexit talks.
A source in May's Conservative Party said talks continued on Friday. May in return for the DUP's support, but there are indications the party will be seeking more funding for Northern Ireland programs as well as a softer line on Brexit talks.
Most importantly, with Northern Ireland having voted to remain in the European Union while the United Kingdom as a whole voted out, the DUP has won agreement that will ensure a "frictionless" border between Northern Ireland and the Republic of Ireland.
"My clear view, and I believe the view of the majority of people in Britain, is that we should prioritize protecting jobs, protecting economic growth, protecting prosperity as we enter those negotiations", Hammond told reporters before a meeting of the 28 European Union finance ministers in Luxembourg. "I think it's unlikely there will be any announcement today", a DUP spokesman said.
May, will then travel to Paris for a working dinner with French President Emmanuel Macron before the two leaders attend a friendly football match between England and France at the national stadium in Paris.
Labour leader Jeremy Corbyn is pushing for this outcome, and has repeatedly said he was ready to try to form a government. May appointed Steve Baker, a prominent Brexit campaigner, to the Department for Exiting the EU."We need a good, clean exit which minimises disruption and maximises opportunity", Baker said just hours before his appointment.
During the complex talks, the two sides will also have to negotiate a new customs and trade regime between the single market and the UK.
Ministers have already said that the Queen's Speech may have to be set back from its scheduled date of next Monday because of the ongoing negotiations.
The European Parliament's Brexit negotiator, Mr Guy Verhofstadt, also expressed his frustration.