Tannin-boron based preservative solutions were used for the treatment of D. asper bamboo by vacuum/pressure impregnation. Samples treated with tannin/hexamine-based solutions presented low weight losses after decay tests with P. sanguineus and G. trabeum decay fungi, and were classified as resistant and highly resistant, respectively, even after leaching. However, a high boron loss after severe leaching cycles was observed. Samples treated with tannin/hexamine/boron had superior mechanical properties and increased thermal stability. The use of tannin-based solutions in combination with boron compounds showed promising results in terms of mechanical properties improvement and increased fungal decay resistance, bringing new possibilities for bamboo preservation.