Photographs posted on the Syrian presidency's Facebook page showed the president along with his wife, Asma, standing with nuns and orphans in the Damascus suburb of Sednaya.
In the northern city of Aleppo, Christians celebrated Christmas for the first time in four years with the country's largest city now under full control of government forces, the Associated Press reported.
The rebel withdrawal from east Aleppo last week marked President Assad's biggest victory since Syria's foreign-sponsored war began in 2011.