The Ligue 1 winners, who suffered a shock defeat by Botafogo on Friday and were guaranteed a spot in the last 16 with a win over Seattle, scored in each half through Khvicha Kvaratskhelia and Achraf Hakimi.
With the result, PSG finished with six points from three games in the group stage.
Seattle, who needed to beat PSG by a margin of three goals or more to stand a chance of progressing, exit the CWC winless after three games played in their home stadium, Lumen Field in Seattle, Washington.
It took nearly the entire second half, but relentless attacks on goal paid off for Antoine Griezmann in the 87th minute as the France international striker earned Atletico Madrid to a 1-0 victory over Botafogo in Group B.
After teammate Angel Correa's shot was blocked by a defender, Griezmann sent a left-footed shot into the net.
That was not enough to send the Spaniards into the last 16 as Atletico needed a victory of at least three goals to advance.
**Reuters-Field Level Media**