Good Friday Agreement
The Undertones singer said the Good Friday Agreement showed what "peace, prosperity and diplomacy and democracy looks like".
The US president met with prime minister Rishi Sunak during the visit.
The US president addressed an audience in Northern Ireland to mark the 25th anniversary of the Good Friday Agreement.
US President Joe Biden is visiting Northern Ireland to honour 25 years since the treaty was signed.
No.10 dismissed claims Rishi Sunak and Joe Biden's meeting in Northern Ireland was being kept "low-key".
The former British prime minister admitted there were some things they could have done differently during the "rollercoaster" negotiations.
The DUP and Tory backbenchers are now poring over the details of Windsor Framework.
The Tory MP used a podcast to tell the prime minister where he was going wrong in his bid to reach a new Northern Ireland Brexit deal.
US President-elect had previously said the Good Friday Agreement must not "become a casualty of Brexit".
President-elect spoke to Irish Taoiseach Micheál Martin as well as Boris Johnson on Tuesday.