The radial distribution system (RDS) carries the bulk of consumer load and, owing to its topology and high R/X ratio, suffers from significant active power loss and a poor voltage profile that degrades toward the feeder ends. Maintaining an acceptable voltage profile is therefore a primary concern for distribution utilities. This paper presents the analysis and improvement of the voltage profile of a standard IEEE 33-bus RDS through optimal placement and sizing of distributed generation (DG). A single-objective optimization problem is formulated by combining active power loss and a voltage stability index into one objective through weighting factors, subject to voltage-limit and DG-size constraints, with a Gauss–Seidel load flow used to evaluate candidate solutions. Seven metaheuristic algorithms—Particle Swarm Optimization (PSO), Ant Lion Optimization (ALO), Whale Optimization Algorithm (WOA), Moth Flame Optimization (MFO), Marine Predator Algorithm (MPA), Sine Cosine Algorithm (SCA) and Gold Rush Optimization (GRO)—are implemented and compared. With a single 2000 kW DG placed at bus 7, the minimum bus voltage rises from 0.9131 p.u. to about 0.943–0.963 p.u. and the total active power loss falls from 202.66 kW to 107.95 kW. Most algorithms converged to highly similar near-optimal solutions but differ in accuracy and computation time; WOA and SCA demonstrated competitive solution quality with favourable computational performance.