Arlo (pronounced AR-loh) is a given name for males. There are several origins of the name. From Old English, it is a variation of Harlow /HA(r)-low/, derived from the Anglo-Saxon here 'army, troops; war-' and hlaw 'mound, cairn, hill,' thereby meaning 'army hill.' In Italian it can be a variant of Carlo(s), Karlo(s), equivalent to the English name Charles, which in turn is derived from Middle High German karl 'man.' In Spanish, its meaning is 'barberry tree.' Arlo can also be a variant of Harley and the first formant in Arlene, which derive from Old English har "hare", "rabbit" and ear(n) "eagle." The second formant, giving -lo(w), -l(e)y, etc. are topographic names, such as the hlaw mentioned above. For example, the ancestors of today's lee (and name Lee), loch, etc. As such, names like Harley, Arlo, etc. can also mean "eagle's hill," "hare's clearing," and so on.

Variant forms of Arlo include: Arlow, Arlowe, Arrlo, Harlow and Harlowe.