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Four polyoxygenated stigmastanes (<b>1</b>–<b>4</b>) alongside known analogues (<b>7</b>–<b>8</b>) and flavonoids (<b>5</b>–<b>6</b>) were isolated from a dichloromethane/methanol (1:1, <i>v</i>/<i>v</i>) extract of the whole plant of <i>Vernonia kotschyana</i> Sch. Bip. ex Walp. (Asteraceae). Their structures were determined by means of spectroscopic and spectrometric analysis. The relative stereochemistry of the new compounds was established and confirmed via biosynthesis evidence and cyclization of <b>1</b> under acidic conditions. A plausible biosynthetic pathway to the new compounds and the chemophenetic significance of the isolated constituents were also discussed. The crude extract, fractions, and compounds (<b>1</b>–<b>3</b>) were assessed for their antibacterial activity against five highly prevalent bacterial strains. The fractions and compounds showed low to moderate activity with minimal inhibitory concentrations (MICs) > 125 µg/mL.