The 24-year-old Spaniard weathered some fierce early hitting by the powerful Soderling before taking command on Court Philippe Chatrier and surging to victory in two hours 18 minutes.
Nadal was in a miserly mood against the man who stunned him in last year's fourth round, his only defeat at Roland Garros, and Soderling's challenge fizzled out in disappointing fashion.
Soderling, last year's runner-up, could find no way through Nadal's defences and once he dropped serve in the fifth game of the first set the outcome seemed inevitable.
Nadal, who now has seven Grand Slam titles to his name, wrapped up victory when Soderling netted a backhand before collapsing on to his back and clenching his fists.