Gate isolation methods and structures for a FinFET device leverage the definition and formation of a gate cut opening within a sacrificial gate layer prior to patterning the sacrificial gate layer to form a sacrificial gate. The gate cut opening formed in the sacrificial gate layer is filled with a sacrificial isolation layer. After forming source/drain junctions over source/drain regions of a fin, the sacrificial isolation layer is replaced with an isolation layer, and the sacrificial gate is replaced with a functional gate.