Continuous physiological signal monitoring is often disrupted by motion artifacts and mechanical noise, requiring signal processing that can distort signals. Here, we present viscoelastic polyborodimethylsiloxane (PBDMS)-based mechanical pass filters with stable damping performance for over three months. Dynamic hydrogen and B–O bonding enable energy dissipation through chain rearrangement, while molecular-weight-dependent relaxation allows precise tuning of transition frequencies. By parallel assembly of PBDMS with distinct phase behaviors, high-pass, low-pass, and band-pass mechanical filtering is achieved. Integrated into wearable bioelectronics, these filters separate multiple concurrent mechanical signals without additional signal processing.