Psalm 98 is the 98th psalm of the Book of Psalms, beginning in English in the King James Version: "O sing unto the Lord a new song; for he hath done marvellous things". The Book of Psalms starts the third section of the Hebrew Bible, and, as such, is a book of the Christian Old Testament. In the slightly different numbering system in the Greek Septuagint version of the Bible, and in the Latin Vulgate, this psalm is Psalm 97. In Latin, it is known as "Cantate Domino". The psalm is a hymn psalm, one of the Royal Psalms, praising God as the King of His people. Like Psalms 33 and 96, it calls for the singing of "a new song".

The psalm forms a regular part of Jewish, Catholic, Lutheran, Anglican and other Protestant liturgies. It has inspired hymns such as "Joy to the World" and "Nun singt ein neues Lied dem Herren", and has often been set to music, including by Claudio Monteverdi, Marc-Antoine Charpentier, Dieterich Buxtehude and Antonín Dvořák who set it in Czech in his Biblical Songs.

Psalm 98 describes God's redemption of Israel and the rejoicing that will ensue. It also features many expressions and instruments of music and song. According to the Midrash Tanchuma, Psalm 98 is the tenth and final song that the Jewish people will sing after the final redemption. Grammatically, the reference to a shir chadash (Hebrew: שיר חדש, a new song) in verse 1 is a masculine construction, in contrast to the shira (Hebrew: שירה, song) mentioned throughout the Tanakh, a feminine construction. Thus, the Midrash teaches that the shir chadash is a song of the future.

Verse 3 is quoted in Mary's song of praise, the Magnificat, in Luke 1:54.

Psalm 98 is the fourth of six psalms recited during the Kabbalat Shabbat (Welcoming the Shabbat) service in Ashkenazic, Hasidic and some Sephardic communities. It is one of the additional psalms recited during the morning prayer on Shabbat in the Sephardi tradition. According to the Abudraham, this psalm corresponds to the seventh of the Ten Utterances of Creation, "Let the waters swarm" (Genesis 1:20), corresponding to verse 7 of this psalm, "Let the sea roar".

Verse 6 is one of the ten verses recited during the Mussaf Amidah on Rosh Hashana in the verses of Shofarot.

The psalm may be recited as a canticle in the Anglican liturgy of Evening Prayer according to the Book of Common Prayer as an alternative to the Magnificat, when it is referred to by its incipit as Cantate Domino. It is not included as a canticle in Common Worship, but it does of course appear in the psalter.

In the Agpeya, the Coptic Church's book of hours, this psalm is prayed in the office of None.