Many crucial components inside electronic devices are made from non‐renewable, non‐biodegradable, and potentially toxic materials, leading to environmental damage. Finding alternative green dielectric materials is mandatory to align with global sustainable goals. Carboxymethyl cellulose (CMC) is a bio‐polymer derived from cellulose and has outstanding properties. Herein, citric acid, dextrin, and CMC based hydrogels were prepared, which are biocompatible and biodegradable and exhibit rubber‐like mechanical properties, with Young modulus values of 0.89 MPa. Hence, thin film CMC‐based hydrogel is explored as a suitable green high‐k dielectric candidate for operation at low voltages, demonstrating a high dielectric constant of up to 78. These fabricated transistors reveal stable high capacitance (2090 nF cm−2) for around ±3 V operation. Using a polyelectrolyte‐type approach and poly‐(2‐vinyl anthracene) (PVAn) surface modification, this study demonstrates a thin dielectric layer (d ≈ 30 nm) with a small voltage threshold (Vth ≈ ‐0.8 V), moderate transconductance (gm ≈ 65 nS), and high ON‐OFF ratio (∼ 105). Furthermore, the dielectric layer exhibits stable performance under bias stress of ± 3.5 V and 100 cycles of switching tests. The modified CMC‐based hydrogel demonstrates desirable performance as a green dielectric for low‐voltage operation, further highlighting its biocompatibility.This article is protected by copyright. All rights reserved