Watermarking strategies are widely used to preserve the patient identity and copyright of a patient’s clinical records. This work provides a new blockchain-based watermarking approach using the IWT. For the proposed scheme, the distributed nature of blockchain makes it more secure. With a consensus mechanism, the data integrity and authenticity will be preserved when watermarked images are extracted at the receiver end using a watermarked hash ID and shared secret key stored in the blockchain. Several analytical techniques have been utilized to evaluate the suggested scheme. A shared secret key ( \(\delta \) ), user key ( \(\gamma \) ), and SHA-512 have been utilized to enhance the security of the suggested approach. Fibonacci and Non-Fibonacci series are used for the embedding process to embed the watermark bit. The proposed scheme achieved a 53.57 dB PSNR value and, an MSE value of 489.32 which is better than the other advanced blockchain-based approaches. The experimental analysis shows that the suggested model is more effective than some modern techniques in terms of visual quality and security of medical images.