The EU and UK's joint priority is the "timely and faithful implementation" of all elements of the Windsor Framework, Maros Sefcovic has said.
The European Commission vice-president was speaking on Monday during the EU-UK Forum Annual Conference.
His remarks came nearly four months since Brussels and London announced their breakthrough deal on the Northern Ireland Protocol.
Mr Sefcovic described February's agreement as a "deliberate and careful balance, granting flexibilities on the condition that agreed safeguards are in place".
He said a "comprehensive set of joint solutions" had been agreed through a "constructive, creative and collaborative approach" under the leadership of President Ursula von der Leyen and Prime Minister Rishi Sunak.
The commission vice-president expressed personal thanks to UK interlocutors James Cleverly and Chris Heaton-Harris.
He said the framework's solutions cut across many sectors, including agrifood, medicines and customs.
"They are designed to address in a definitive manner the challenges experienced by people and businesses on the ground," he said.
Mr Sefcovic said an important element of the EU-UK deal was "enhanced stakeholder engagement".
"The Windsor Framework preserves the integrity of both the EU's Single Market and Northern Ireland's integral place in the United Kingdom's internal market," he said.
"And, crucially, it will maintain the foundations of peace by avoiding a hard border on the island of Ireland."
He said the framework was put in place "in full respect of the legitimate interests of both the EU and the UK".
"But our work did not finish with agreement on the Windsor Framework," the vice-president said.
"Our joint priority now is the timely and faithful implementation of all its elements."
Mr Sefcovic highlighted recent developments relating to the implementation of the framework, including the commission publishing the implementation measures for the customs simplifications for the movement of goods not at risk and for parcels.
"There is a lot of work still to be done but I am confident that our joint collaborative approach will continue to bear fruit," he told the online conference.
The EU's chief protocol negotiator also stressed the value of the December 2020 Trade and Cooperation Agreement (TCA), which governs EU-UK relations on matters such as trade, transport, fisheries and energy.
"The TCA offers significant potential to further improve our partnership," he said.
"However, it is not – and can never be – a replacement for EU membership."
He said trade can no longer be as frictionless and dynamic as when the UK was an EU member and that this "inevitably means additional costs for businesses on both sides".
"Over time, increased divergence may bring even more cost and will further deepen the barriers to trade between the EU and the UK – this is regrettable but must be accepted," Mr Sefcovic said.
