In Genesis 3:24, it is a Cherubim - an angel of the Lord who guards the Garden of Eden. They are depicted in the tabernacle and on the ark of the covenant, guarding the Throne of God. In all places, they are associated with angelic beings and are part of the host of heaven.
The difficulty in giving a verse calling a cherubim an angel is that angelos is a Greek word defining the job of a heavenly being (messenger). Cherubim are guards, not messengers. So, at the time of writing, cherubim would not have been Angelos.
But Angel has come to mean any heavenly being. Can we say that cherubim are heavenly beings? Yes. Clearly, for the reasons stated above. Can we say they are messengers? No. But in popular parlance, are angels just messengers or are they any kind of heavenly being? I would argue the popular notion of the word is that second definition - but that second definition doesn't come about until after the Scriptures are written. As such, you have to say Cherubim are what Angels have become.
Note, for example, from the Holman Bible Dictionary:
CHERUB or CHERUBIM (Chĕrʹ ŭ·bĭm) Class of winged angels.
And yet, an Angel is, by the same book's definition:
ANGEL Created beings whose primary function is to serve and worship God. Though some interpret the “us” in Gen. 1:26 as inclusive of God and His angelic court, the Bible does not comment as to when they were created. Unlike God they are not eternal or omniscient. The Hebrew word in the OT is malʾak, and the NT Greek word is angelos. They both mean “messenger” and occasionally refer to human messengers.
Holman goes on to say of cherubim:
The Hebrew cherub (plural, cherubim) is of uncertain derivation. In the OT it is the name of a class of winged angels who functioned primarily as guards (Gen. 3:24) or attendants (Ezek. 10:3–22). The only NT reference to cherubim is in a description of the furnishings of the holy of holies (Heb. 9:5).
Texts descriptive of the appearance and activities of cherubim reflect two contexts. One is in the visions of the presence of God attended by living creatures (cherubim and seraphim, Isa. 6:2–6; Ezek. 1:4–28; 10:3–22). The other is temple worship and the representations of cherubim which were a part of its furnishings (Exod. 25:18–22; 1 Kings 6:23–35; 2 Chron. 3:7–14).
The most impressive of the temple cherubim were the large sculptures (probably winged quadrupeds) in the holy of holies. If these were arranged as was common in the ancient Near East, the two cherubim would together form a throne. Their legs would be the legs of the throne, their backs the arm rests, and their wings the back of the throne. Consistent with the idea of a cherub throne are the texts which envision God dwelling between, enthroned upon, or riding upon the cherubim (1 Sam. 4:4; 2 Sam. 6:2; 22:11; 2 Kings 19:15; 1 Chron. 13:6; 28:18; Pss. 18:10; 80:1; 99:1; Isa. 37:16). Even Ezekiel’s vision depicts the glory of God resting upon or between the cherubim as something of a living throne. See Angels.
In popular Christian understanding, cherubim (Ezekiel) and seraphim (Isaiah) are both kinds of angels. They are created beings who serve in the presence of God.
Take, for example, the classic hymn "Holy, Holy, Holy,"
Holy, holy, holy! All the saints adore Thee,
Casting down their golden crowns around the glassy sea;
Cherubim and seraphim falling down before Thee,
Who was, and is, and evermore shall be.
This text draws on imagery from revelation in which the entire host of heaven - angels and the resurrected saints, are all worshipping God.
