Cameron and Jeremy Corbyn, leader of the opposition Labour Party, laid flowers in front of a statue in the town of Birstall, close to where Jo Cox, 41, died.
They announced that Parliament was being recalled on Monday in sign of respect. In the U.K., the government can ask the speaker to recall the House of Commons because of events of major national importance.
"Parliament will be recalled on Monday so that we can pay due tribute to her on behalf of everybody in this country who values democracy, values the right of free speech and values the right of political expression, free from the kind of brutality that Jo suffered,” Corbyn said, speaking to reporters after the tribute.
Campaigning on the E.U. "brexit" referendum -- which is set for June 23 -- was temporarily suspended following her death. Cameron said it was a moment to "stand back" and "think about some of the things that are so important about our country."
"If we truly want to honor Jo, then what we should do is recognize that her values - service, community, tolerance - the values she lived by and worked by, those are the values that we need to redouble in our national life in the months and years to come,” Cameron said.
Cox was seen as a rising star of the Labour Party. Following her death, the Conservative Party has decided not to contest the forthcoming election in her constituency as a mark of respect.
Police tell ABC News that they are still questioning a 52-year-old man who was arrested shortly after the attack. No other suspects are being investigated, police said.
There will be a vigil in memory Cox in the Chapel of St Mary Undercroft in Westminster this evening followed by a vigil in Parliament Square.