14th century, in the meaning defined at sense 11550, in the meaning defined at intransitive sense

Middle English chariot, chariette "wheeled vehicle for transporting people or things, vehicle used in warfare," borrowed from Anglo-French, "four-wheeled vehicle" (also continental Old French), from charier "to transport, carry entry 1" + -ot, noun suffix, here instrumental, going back to Vulgar Latin *-ottus, variant of Latin -ittus, diminutive suffix

NOTE: Other examples of -ot as an instrumental suffix are brûlot "fireship," cachot "prison cell."

derivative of chariot entry 1