Oman is one of the rare Arab countries that kept diplomatic relations with the Syrian government of President Bashar al-Assad after the start of the 2011 foreign-backed militancy, despite pressure from the United States and other Persian Gulf allies.
Syria's foreign minister Sunday accepted the credentials of Oman's Ambassador Turki bin Mahmood al-Busaidy, appointed to the post in a royal decree in March, state news agency ONA said, Reuters reported.
Some Arab states are seeking reconciliation with Damascus after decisive gains by pro-government forces in the conflict.
Oman, whose Sultan Haitham pledged when assuming power in January to continue maintaining friendly ties with all nations, kept its embassy open, as did Bahrain.
The United Arab Emirates re-opened its mission to Damascus in late 2018 in a diplomatic boost to Assad, and has a charge d'affaires there.
The UAE was one of several regional states to back rebel groups in Syria, though its role was less prominent than those of Saudi Arabia and Qatar, which have so far held off re-establishing ties with Damascus.
Kuwait has said it would re-open its mission in Damascus if there is agreement in the Arab League, which suspended Syria's membership in 2011.