In this work, we demonstrate the high-yield synthesis of carbon quantum dots using a one-step low-cost thermal treatment of a renewable biomass, i.e. natural chia seeds. The synthesized carbon dots (C-dot) exhibited tunable photoluminescence with high quantum yield in the range of 4-25% for various solvents. The physicochemical characterization revealed that the synthesized carbon quantum dots were amorphous in nature with their sizes ranging from 2-6 nm. The synthesized carbon dots could be further extracted up to five times from the same pyrolized product using a facile route, which has endowed the synthesis with high yield. Moreover, the rationale behind the multicolor fluorescence emission due to solvation effects was studied systematically using photoluminescence spectra (PL) and the origin of PL shifts of the carbon dots in different solvents was discussed in regard to the contribution from hydrogen bonding and dipole-dipole interactions. The presented study aims at developing a green approach, which could be readily adapted for the scalable production of carbon dots capable of long-range emission for utilization in bio imaging, photothermal therapy and multifunctional sensing systems. © 2017 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.