The objective of this research was to evaluate the effect of bamboo species and resin content on the physical and mechanical properties of oriented strand boards (OSBs) prepared from steam-treated bamboo strands. The strands from three species of Indonesian bamboo, namely Andong (Gigantochloa verticillata), Betung (Dendrocalamus asper), and Ampel (Bambusa vulgaris), were steamed at 126 °C for 1 h at a pressure of 0.14 MPa. Three-layered OSBs with the core layer oriented perpendicularly to the face layers were prepared by bonding them together with 3 to 5% methylene diphenyldiisocyanate (MDI) resin based on oven-dried strands and with the addition of 1% paraffin. The strand compositions for the face, core, and back layers were 25%, 50%, and 25%, respectively. The slenderness ratios and aspect ratios of the strands ranged from 71.02 to 76.60 and from 2.96 to 3.02, respectively. The physical and mechanical properties of the OSBs fabricated from Andong and Betung were better than those from Ampel, and the properties of all OSBs were improved by increasing their resin content. OSBs from Betung with 3 to 5% resin content and those from Andong and Ampel with 4 to 5% resin content showed strength retention of more than 50%, which means they can be used for exterior structural applications. Except for OSBs fabricated from Ampel with 3% resin content, the properties of all OSBs prepared in this study were higher than the minimum values required by the CSA O437.0 (grade O-1) standard (2011).