The cancellation has angered France, which accused both Australia and the United States of stabbing it in the back, and it recalled its ambassadors from both Canberra and Washington
Negotiated in marathon talks by EU and US officials, the truce will be formalised in Biden's summit with European leaders Charles Michel and Ursula von der Leyen.
"Both sides must implement what we agreed on," von der Leyen, European Commission president, said after meeting Johnson alongside Michel, the European Council president.
"There is complete EU unity on this," she said, adding that the deal had been agreed, signed and ratified by both Johnson's government and the bloc.
Michel said he would discuss with Georgian political leaders joint steps aimed at strengthening the ties between Brussels and the EU-aspirant nation in Europe's extreme southeast.
EU diplomats said that leaders last week urged Michel to cancel the in-person meeting, though he had hoped to tighten sanitary measures to avoid reverting again to a videoconference.
Under the EU deal, musicians are not covered by exemptions allowing for free passage of short-term business visitors, sparking warnings that continental tours by UK bands will become unviable.
Michel said the technique should be backed up with "antigen tests, which -- although currently regarded as less reliable -- are more efficient, yielding results within 15 minutes."
The two sides agreed to open negotiations during a three-way videoconference between Turkish President Recep Tayyip Erdogan, German Chancellor Angela Merkel .