Described herein are benzoxazepin oxazolidinone compounds with phosphoinositide-3 kinase (PI3K) modulation activity or function having the Formula I structure: or stereoisomers, tautomers, or pharmaceutically acceptable salts thereof, and with the substituents and structural features described herein. Also described are pharmaceutical compositions and medicaments that include the Formula I compounds, as well as methods of using such PI3K modulators, alone and in combination with other therapeutic agents, for treating diseases or conditions that are mediated or dependent upon PI3K dysregulation.