Novel palladium(II) and platinum(II) complexes (trans-[PdCl₂L₂] and trans-[PtCl₂L₂] {L = 2-(5-methyl-1H-tetrazol-1-yl)acetamide, N-(sec-butyl)-2-(5-methyl-1H-tetrazol-1-yl)acetamide, N-cyclopropyl-2-(5-methyl-1H-tetrazol-1-yl)acetamide, N-cyclohexyl-2-(5-methyl-1H-tetrazol-1-yl)acetamide, 2-(2-(tert-butyl)-2H-tetrazol-5-yl)acetamide and 2-(2-(tert-butyl)-2H-tetrazol-5-yl)-N-cyclohexylacetamide} 1b–6b and 1c–4c) were synthesized and characterized by elemental analyses (CHN), HRESI⁺-MS, ¹H, ¹³C{¹H}, ¹⁹⁵Pt NMR and IR spectroscopies, DSC/TG analysis, as well as by X-ray single crystal diffraction {for (2-(5-methyl-1H-tetrazol-1-yl)acetamide) 1a·H₂O, trans-[PdCl₂(2-(5-methyl-1H-tetrazol-1-yl)acetamide)₂] 1b, trans-[PdCl₂(N-cyclopropyl-2-(5-methyl-1H-tetrazol-1-yl)acetamide)₂] 3b and trans-[PdCl₂(N-cyclohexyl-2-(5-methyl-1H-tetrazol-1-yl)acetamide)₂] 4b}. The binding of complexes 2b and 5b to calf-thymus DNA (CT DNA) and BSA (bovine serum albumin) was studied by means of CD, UV and fluorometric techniques. According to the spectroscopic data, an interaction of the metal complexes with CT DNA was confirmed. A significant increase in the melting point of CT DNA in the presence of the metal complexes {ΔT_m = 10.0 °C (for 2b), 12.5 °C (for 5b)} indicates a strong stabilization of the DNA helix. According to the fluorometric data, complex 2b exhibits an interaction with BSA. Additionally, molecular docking results suggest that complex 1b and its fully hydrolyzed form (trans-[Pd(H₂O)₂(2-(5-methyl-1H-tetrazol-1-yl)acetamide)₂]) cooperatively interact with DNA, presumably via minor groove binding. The hydrolyzed form possesses a greater affinity to DNA. Also, there is an effective interaction of complex 1b and the corresponding hydrolyzed form to BSA via the two binding sites Trp134 and Trp213. Two complexes {trans-[PdCl₂(N-(sec-butyl)-2-(5-methyl-1H-tetrazol-1-yl)acetamide)₂] 2b and trans-[PdCl₂(2-(2-(tert-butyl)-2H-tetrazol-5-yl)acetamide)₂] 5b} demonstrate antiproliferative activity against human cancer cell lines, with IC₅₀ = 45 ± 0.5 µM for 2b on HeLa and IC₅₀ = 44.3 ± 0.8 µM for 5b on MCF-7. The complexes 4b, 4c and 6b were evaluated for their antimicrobial activity against Escherichia coli (strain КA796) and they showed significant activities, being greater than that of cisplatin. Complex 4b was the most effective, with the lowest MLC value of 0.25 µM and LC₅₀ value of 0.075 µM.