Herein, the first lead fluorooxoborate PbB₅O₈F has been structurally designed following a strategy of fluorine introduction into borates. PbB₅O₈F presents the first case of possessing the [B₅O₁₀F]⁶⁻ fundamental building block. More importantly, PbB₅O₈F fully achieves the coexistence of large birefringence and deep-ultraviolet cut-off edge. This short cut-off edge sets a new record among lead borates.