Sweden made nine changes in Hamilton and lacked the coherence of their previous two games, but they still had too much for their opponents.
Sweden's added skill shone through after a tightly contested hour, with Rebecka Blomqvist finding space in the box to force home Sofia Jakobsson's close-range cross.
Elin Rubensson put the game out of reach with a calm late penalty after Blomqvist was tripped in the box as Argentina attempted to defend a free-kick.
Argentina is out of the competition after finishing last in their group with one point.
They fought hard here but were unable to harm the Swedes and achieve what would have been a historic double at a World Cup final: a first-ever win and advancement to the knockout rounds.
South Africa joined the Swedes in the last 16 after a thrilling 3-2 victory against Italy in Wellington.">