We present REMARK-LLM, a novel efficient, and robust watermarking framework designed for texts generated by large language models (LLMs). Synthesizing human-like content using LLMs necessitates vast computational resources and extensive datasets, encapsulating critical intellectual property (IP). However, the generated content is prone to malicious exploitation, including spamming and plagiarism. To address the challenges, REMARK-LLM proposes three new components:(i) a learning-based message encoding module to infuse binary signatures into LLM-generated texts;(ii) a reparameterization module to transform the dense distributions from the message encoding to the sparse distribution of the watermarked textual tokens;(iii) a decoding module dedicated for signature extraction; Besides, we introduce an optimized beam search algorithm to generate content with coherence and consistency. REMARK-LLM is rigorously trained to encourage the preservation of semantic integrity in watermarked content, while ensuring effective watermark retrieval. Extensive evaluations on multiple unseen datasets highlight REMARK-LLM's proficiency and transferability in inserting 2× more signature bits into the same texts when compared to prior art, all while maintaining semantic integrity. Furthermore, REMARK-LLM exhibits better resilience against a spectrum of watermark detection and removal attacks.