And he rejected a call, by pro-EU Tory Anna Soubry, for MPs to vote if Britain is heading for a "no deal Brexit", replying: "If we don't have an agreement, we can't have a withdrawal agreement Bill".
"Once we have reached an agreement we will now bring forward a specific piece of primary legislation to implement that agreement, this will be known as the withdrawal agreement and implementation bill".
The amendment requiring parliamentary approval of any deal was supported by 10 Tory rebel MPs, who have forced the government's hand on an issue.
He went on: "If we do that, then the withdrawal and treaty vote will come to the House, the simple in principle vote, then as soon as possible thereafter the withdrawal agreement bill will come in front of the House".
What's more, there's no clarity on whether rejecting the bill would mean sending the government back to renegotiate or just result in the United Kingdom going for "no deal" and exiting on WTO terms.
Mr Davis, reiterating comments made previously by ministers, said: "A meaningful vote is a vote which allows you to say you want the deal or you don't want the deal, and that won't be any different".
Tory MP Antoinette Sandbach (Eddisbury) asked Mr Davis how any vote would be meaningful if a deal was only struck on the last day of negotiations. Even if time is on the government's side, there are also so many different parties involved in achieving the final deal that it seems unlikely Parliament could just keep sending Davis back to Brussels until he got is just right. However, it would put Prime Minister Theresa May under pressure to request an extension to negotiations.
Shadow Brexit secretary Sir Keir Starmer said: "This is a significant climbdown from a weak Government on the verge of defeat". They include Dominic Grieve, the Conservative former Attorney General, who previously tabled an amendment to the European Union withdrawal bill demanding a vote. With less than 24 hours before they had to defend their flawed bill to parliament they have finally backed down.
"If they reject the government's Brexit deal, they must have the option to stay in the European Union".