Kikuyu or Gikuyu (Gikuyu: Gĩkũyũ [ɣēkōjó]) (also known as Gĩgĩkũyũ) is a Bantu language spoken by the Gĩkũyũ (Agĩkũyũ) of Kenya. Kikuyu is mainly spoken in the area encompassing the former Central Province (between Nyeri, Kirinyaga, Kiambu, Murang'a and Nyahururu) and surrounding areas like Nairobi, Nakuru and Laikipia. The Kikuyu people traditionally identify their ancestral lands by the surrounding mountain ranges in Central Kenya, including Mount Kenya, which they call Kĩrĩmanyaga and the Aberdare Range.

Symbols shown in angle brackets replace the IPA symbols which are not in the orthography.

The voiceless stops are variously aspirated. The voiced stops /ᵐb ⁿd ᶮdʒ ᵑɡ/ often realized without prenasalisation as [b d dʒ ɡ].

Kikuyu has two level tones (high and low), a low-high rising tone, and downstep.

Kikuyu features a vowel height-based harmony system similar to that in Kiswahili. In verbs, underlying [o] and [e] may appear as [ɔ] and [ɛ] if the root of a word contains either of the latter two. The effect can be shown by contrasting the two verbs: hũrĩra ('hit for') and horera ('cool for'), where neither *horĩra nor *hũrera are possible.

In non-verbs, the [e] of a prefix preceding [i] in a root can morph to [i], shown in rĩ- appearing as riitho ('eye'), and [o] in a prefix appears as [u] when preceding either [u] or [ɔ]. This is shown with the prefix kũ- in the words kuona and kuuma.

Kikuyu is written in a Latin alphabet. It does not use the letters f l p q s v x z, and adds the letters ĩ and ũ. The Kikuyu alphabet is:

Gĩkũyũ has subject–verb–object word order. It uses prepositions rather than postpositions. Nouns are followed by possessive and demonstrative pronouns, which can coexist in that order, and subsequently adjectives, quantifiers, and numerals, which have no order among themselves.