Psiguadiols A-J (<b>1</b>-<b>10</b>), new meroterpenoids with rearranged skeletons, were isolated from the leaves of <i>Psidium guajava</i>. Compounds <b>1</b>-<b>3</b> represent the first examples of 6,8-diformyl-5,7-dihydroxy-4-phenylchromane-coupled sesquiterpenoids with an unprecedented C-8-spiro-fused 6/6/9/4 tetracyclic ring system. Compounds <b>4</b> and <b>5</b> represent two unusual scaffolds featuring 1β,6β- and 3α,5α-epoxy rings, respectively. The combination of spectroscopic data analyses, comparison of experimental and calculated ECD data, and single-crystal X-ray diffraction data of <b>1</b>, <b>6</b>, and <b>8</b> allowed for the assignment of the structures. A putative biosynthetic pathway for <b>1</b>-<b>10</b> is discussed. Compounds <b>1</b>, <b>7</b>, and <b>8</b> exhibited inhibitory activities against PTP1B with IC<sub>50</sub> values of 4.7, 6.2, and 9.2 μM, respectively. In addition, molecular docking was performed to investigate the mechanism of action.