[5] After his death in 1205, the boyars of Galicia forced the four-year-old Daniel into exile with his mother Anna of Byzantium and brother Vasylko Romanovich.

After the boyars proclaimed one of their own as prince, the Poles and Hungarians invaded the principality, ostensibly to support the claims of young Daniel and Vasylko, and divided it between themselves.

Daniel's influence and his alliance with Polish duke Leszek the White made him a competitor to Volodymyr Rurikovich, Prince of Kyiv.

After Leszek's assassination in 1228 Daniel and Vasylko allied with the deceased prince's brother Konrad of Masovia and campaigned tohether with him against Polish duke Władysław Spindleshanks.

[13] On 17 August 1245, Daniel defeated a combined force of the prince of Chernigov, disaffected boyars, and Hungarian and Polish elements at Yaroslav, and finally took the remainder of Galicia, thus reconstituting his father's holdings.

During his rule, German, Polish, and Rus' merchants and artisans were invited into Galicia, and numbers of Armenians and Jews established themselves in the towns and cities.

According to Ukrainian historian Orest Subtelny, Daniel was handed a cup of fermented mare's milk by the Mongol khan, Batu, and told to get used to it, as "you are one of ours now".

[17] While formally accepting the Mongols as overlords, and supplying them with soldiers as required, Daniel built his foreign policy around opposition to the Golden Horde.

[19] The following year, Daniel repelled Mongol assaults led by Orda's son, Kuremsa, on Ponyzia and Volhynia and dispatched an expedition with the aim of taking Kiev.

[14] In the last years of his reign, Daniel engaged in dynastic politics, marrying a son and a daughter to the offspring of Mindaugas of the Grand Duchy of Lithuania and acquiring territorial concessions in Poland from the latter.

[22] On 7 September 2011, the parliament of Ukraine (Verkhovna Rada) issued a resolution on "celebration of the 810th Anniversary of the birth of the first King of Ruthenia-Ukraine Daniel of Galicia".