The development of new lignin-based materials has become a very attractive alternative for researchers due to the particular properties that these can offer and their potential applications. Lignin is biosourced, abundant, biodegradable and renewable, for those reasons, it is an appealing feedstock from which to make materials for diverse applications in diverse fields. Lignin-based nanoparticles may offer properties and morphologies that differ from those of more conventional materials. In this communication, we report the initial results of a new method to produce lignin nanoparticles (LNP) with a tailored particle size using a simple and greener method in which lignin is firstly dispersed at high pH, after which the addition of CO2 at atmospheric pressure precipitates. Two different CO2-responsive amines TMBDA (N,N,N′,N′-Tetramethyl-1,4-butanediamine) and TMTAD (2,6,10-trimethyl-2,6,10-triazaundecane) were evaluated, comparing the effect of each of them on the particle size, and yield. Particle size was in the range of 125-175 nm with narrow particle size distribution for both TMBDA and TMTAD and yield >84% for TMBDA and >94% for TMTAD. This process could increase the use of LNP, leveraging the properties of lignin to enable new bio-based products. Applications of LNP in films and their performance as UV-light shields are also included.