Six new 16-residue peptaibols, acremopeptaibols A-F (<b>1</b>-<b>6</b>), along with five known compounds, were isolated from the cultures of the sponge-associated fungus <i>Acremonium</i> sp. IMB18-086 grown in the presence of the autoclaved bacterium <i>Pseudomonas aeruginosa</i> on solid rice medium. The peptaibol sequences were established based on comprehensive analysis of 1D and 2D NMR spectroscopic data in conjunction with HRESIMS/MS experiments. The configurations of the amino acid residues were determined by advanced Marfey's analysis. Compounds <b>1</b>-<b>6</b> feature the lack of the highly conserved Thr<sup>6</sup> and Hyp<sup>10</sup> residues in comparison with other members of the SF3 subfamily peptaibols. A plausible biosynthetic pathway of compounds <b>1</b>-<b>6</b> was proposed on the basis of genomic analysis. Compounds <b>1</b>, <b>5</b>, <b>7</b>, and <b>10</b> exhibited significant antimicrobial activity against <i>Staphylococcus aureus</i>, methicillin-resistant <i>S. aureus</i>, <i>Bacillus subtilis</i>, and <i>Candida albicans</i>. Compounds <b>7</b>-<b>10</b> showed potent cytotoxicities against the A549 and/or HepG2 cancer cell lines.