Merekotia Amohau was born at Ōhinemutu, Rotorua, on 16 April 1898, the youngest child of prominent Te Arawa leader Hēnare Mete Amohau and his wife, Tūkau Te Hira of Ngāti Pikiao. Known as Mere, she was educated at Ōhinemutu and Maketū, then from 1911 at Queen Victoria School for Māori Girls in Auckland.
As a young woman, Mere embarked on her musical career, guided by F. A. Bennett, superintendent of the Māori mission at Rotorua (later first bishop of Aotearoa), who for many years organised musical performances. Mere played Tupa in Bennett’s Māori Opera Company production of Hinemoa, which opened in Auckland on 2 August 1915 and went on to tour the North Island to mixed reviews. She was invited to play the lead, Mārama, in the comic opera Mārama, or the mere and the Māori maid, which opened in Hastings on 16 November 1920. It was an instant success and played to capacity houses in Hastings and Napier. One audience member recalled Mere ‘gliding across the stage to take her place in front of the Māori haka party and then joining them with great gusto and expertise in a tremendous haka that brought the house to their feet'. Another commented that the opera 'caught people's imagination. We'd come out of the war years and that 1918 epidemic, and here was something New Zealand, something original, something by New Zealanders for New Zealanders’. The melodies and lyrics for the songs, which included 'Mānuka', 'My greenstone tiki' and 'Mārama, maid of the moonlight', were composed by a New Zealander, H. S. B. Ribbands. The show went on to tour the country under the patronage of the governor general, Lord Jellicoe. It was revived in 1940, and Mere Amohau again played the lead role alongside three other members of the original cast.
She was a member of Saint Faith's choir at Ōhinemutu, and of the Rotorua Māori Choir, which toured under Bennett’s direction. Recordings of the Rotorua choir have become collectors' items and in 1930 Mere Amohau recorded Aroha pūmai (I love you truly).
Members of the concert party headed by the renowned Guide Rangi (Rangitīaria Dennan) of Whakarewarewa, Mere Amohau, and her cousin, Guide Hera Rogers, would call into the tourist hotels situated near their residences at Ōhinemutu and charm the guests into attending their concerts. Waiwera House and Hotel Arawa were their favourite hotels, and they never failed to delight patrons with their colourful haka, traditional costumes and warm personalities. During the two world wars they raised funds for local Māori serving overseas.
When the district nursing sister, Robina Cameron, founded Te Rōpū o te Ora Māori Women's Health League on the Tūnohopū marae of Te Arawa in September 1937, Mere Amohau became a foundation member. She was also active in St Faith's women's guild. In the 1940s the Taipōrutu Club was formed, with the aims of promoting Māori culture and community awareness, and supporting tribal affairs. Mere was always available to advise the club leaders. She helped tutor the waiata, composed action songs and performed and travelled with the club. She was a composer of traditional and contemporary Māori music and was one of the foremost authorities on historical chants of Te Arawa.
Mere Amohau had married Rongomaiwhiti Winiata, a clerk, on 4 February 1939, at the vicarage at Ōhinemutu. Mere had three children from other unions and the couple had three more. Rongomaiwhiti died in 1953. Mere died in Rotorua on 30 December 1978. Her tangihanga was held at Tūnohopū marae and she was buried at Kauae cemetery, Ngongotahā.