Multilevel inverters (MLIs) are nowadays extensively used in integration with renewable energy sources and in drives applications. The converter cost and voltage quality improvement are the utmost importance in such application of MLI. A six‐switch seven‐level reduced switch symmetrical MLI (6S‐7L MLI) is proposed here. Compared to the conventional and similar existing MLI topologies, the proposed MLI uses less active switches and has less driver circuit requirement. A particle swarm optimisation (PSO)‐based modified selected harmonic elimination technique is derived and analysed for computing optimal switching angles of proposed 6S‐7L MLI to eliminate third‐ and fifth‐order harmonics. Moreover, the performance of the proposed algorithm is compared with the two most commonly used PSO variants. The analysis shows the modified version of PSO is most suitable for optimising the output voltage of proposed MLI through targeted harmonic elimination. The proposed topology is investigated through simulation by applying the calculated switching angles using modified PSO algorithm. Finally, a single‐phase experimental prototype is designed to verify the validity of the proposed structure.