The European Commission president met the leaders of Hungary, Poland, the Czech Republic and Slovakia – all critical of his plan for ever closer integration.
Mr Juncker posed for a rather awkward picture with the four leaders before heading off for what was described as a “working dinner”.
It marked the first time he had met Bohuslav Sobotka, Viktor Orban, Beata Szydlo and Robert Fico at the commission headquarters.
And the meeting was seen as a crucial effort to try to appease the quartet following months of angry rhetoric.
The group discussed issues of migration, defence, the EU budget and the much criticised Schengen passport-free area.
Mr Juncker tweeted afterwards: “I hosted a working dinner with the #V4 @EU_Commission.
“On the menu: consensus through #compromise and #cooperation. #unity #FutureOfEurope.”
He had invited the group in a letter earlier this month, stressing the “paramount importance” of “a more united, stronger and more democratic Europe”, strained by disputes over immigration and other issues as well as by Brexit.
Mr Juncker wrote: “I believe that preserving the unity of the 27 in this process is of paramount importance.”
Warsaw and Budapest have constantly been at loggerheads with the bloc’s executive Commission in Brussels, as well as with EU heavyweights Germany and France, over what the bloc increasingly sees as their flouting of democratic rules.
The eastern states, especially Poland and Hungary, have resisted an EU program for all member states to accept refugees after a mass influx of people in 2015-16, mostly Muslims from the Middle East and Africa.
Other points of contention include a reform of EU’s labor rules, which France and some other western states say give unfair competitive advantage to cheap workers from the east.
And today’s meeting came amid warnings Austria could try to join the group following its election.
Sebastian Kurz is set to become the continent’s youngest leader after his Austrian People’s Party topped the polls after Sunday’s vote.
He may need to form a coalition with the far-right Freedom Party (FPO) to secure a government, something the EU appears keen to avoid.
And there are suggestions the FPO could insist Austria joins the Visegrad group.