We present a facile room temperature synthesis of CH3NH3Pb1-xMnxI3 perovskite quantum dots (PQDs) substituting manganese (Mn2+) at the lead (Pb2+) sites to minimize environmental pollution and make it commercially feasible. By varying the concentration of Mn2+ from 0 to 60%, the PQDs exhibit strong color tunability from red to orange color suggesting successful energy transfer due to Mn2+ inclusion. We observed a high external photoluminescence quantum yield (PLQY) of 98% for unsubstituted CH3NH3PbI3 and >50% for up to 15% Mn2+ substituted PQDs. The average lifetime of PQDs was found to shorten with increasing Mn2+ replacement. We demonstrate a white LED prototype by employing the CH3NH3Pb1-xMnxI3 PQDs with green QDs on a blue LED chip. The CRI and CCT value varying from 92 to 80 and 5100 K to 2900 K, respectively, indicate the usability of the Mn2+ substituted PQDs as efficient warm white LEDs with a promising CRI and good stability.