Lignin, a complex biopolymer in plant cell walls, plays a crucial role in plant defense against pathogens. This review discusses the recent progress in understanding lignin biosynthesis and its diverse roles in plant disease resistance. Lignin biosynthesis involves a series of biochemical reactions that convert phenylpropanoids into monolignols, which polymerize to form lignin. The composition and content of lignin vary among different plant species and tissues, and these variations influence disease resistance. Lignin acts as a physical barrier to restrict pathogen entry and nutrient transmission, and its accumulation can enhance disease resistance. Additionally, lignin-related compounds, such as phytoalexins and lignans, can activate plant immune responses. Several genes involved in lignin biosynthesis, including those encoding enzymes like caffeoyl shikimate esterase (CSE) and ferulate 5-hydroxylase (F5H), have been identified to play key roles in plant defense. Transgenic studies have shown that altering lignin content or composition can affect disease resistance. The review also highlights the involvement of transcription factors, such as MYB and ROP GTPases, in regulating lignin biosynthesis and immune responses. Understanding these mechanisms will aid in developing crops with broader disease resistance through molecular breeding strategies.Lignin, a complex biopolymer in plant cell walls, plays a crucial role in plant defense against pathogens. This review discusses the recent progress in understanding lignin biosynthesis and its diverse roles in plant disease resistance. Lignin biosynthesis involves a series of biochemical reactions that convert phenylpropanoids into monolignols, which polymerize to form lignin. The composition and content of lignin vary among different plant species and tissues, and these variations influence disease resistance. Lignin acts as a physical barrier to restrict pathogen entry and nutrient transmission, and its accumulation can enhance disease resistance. Additionally, lignin-related compounds, such as phytoalexins and lignans, can activate plant immune responses. Several genes involved in lignin biosynthesis, including those encoding enzymes like caffeoyl shikimate esterase (CSE) and ferulate 5-hydroxylase (F5H), have been identified to play key roles in plant defense. Transgenic studies have shown that altering lignin content or composition can affect disease resistance. The review also highlights the involvement of transcription factors, such as MYB and ROP GTPases, in regulating lignin biosynthesis and immune responses. Understanding these mechanisms will aid in developing crops with broader disease resistance through molecular breeding strategies.