Guanidine is widely used in biochemistry and molecular biology as a protein denaturant. It disrupts hydrogen bonds and hydrophobic interactions, effectively unfolding proteins, which is crucial for studying protein structure and function.

In the pharmaceutical industry, it serves as a key intermediate in the synthesis of various drugs, including antiviral and antihypertensive medications.

Additionally, guanidine derivatives are employed in the production of dyes, resins, and explosives.

Its strong basic properties also make it useful in organic synthesis, particularly in the preparation of heterocyclic compounds.

In agriculture, guanidine-based compounds are utilized as fertilizers and plant growth regulators, enhancing crop yield and quality.