Ashby Magna, in the Guthlaxton Hundred of Leicestershire, is likely an Anglo-Scandinavian name coming from Old English æsc ‘ash-tree’ and Old Norse by ‘a farmstead, a village’. Some spellings may show influence of Old Norse eski ‘a place growing with ash-trees’ or even Old English esce ‘a stand of ash-trees’ on the first element.

Ashby is a common place-name, but is is uncertain whether this name is an Old English creation Scandinavianized (i.e replacing Old English tun ‘an enclosure; a farmstead; a village; an estate’ with Old Norse by) or whether the name is fully Scandinavian in origin, with Old English æsc (Middle English ash) replacing Old Norse askr ‘ash-tree’.

The affix Medieval Latin magna ‘great’ differentiates the township from Ashby Parva, which lies approximately three miles to the south-west.