This chapter addresses Nigeria as the country most fragile and vulnerable to decarbonisation among the case study countries chosen for the present study. The fortunes of Nigeria’s economy are closely tied to the oil price, making it vulnerable to oil market fluctuations and the phase-out of fossil fuels. While its oil and gas reserves have brought huge wealth to the country, the profits and benefits have not been equitably shared or sufficiently invested in key public services and infrastructure. The chapter demonstrates that this underinvestment coupled with other major challenges has held back efforts to diversify the economy, despite significant existing potential. Although efforts to increase and liberalise EU-Nigeria trade in non-oil sectors have stalled, there is plenty of scope for the EU to support Nigeria in sustainably developing its non-oil economy. There are numerous entry points for political dialogue and development cooperation to enable the EU to advance its relations with Nigeria under decarbonisation. These relate to Nigeria’s many pressing security, economic, and socio-political issues and to the promotion of a decarbonised economy.