Wolves suffered a crushing 3-0 defeat at Fulham on Saturday, extending their winless run to 10 league games with just two points from a possible 30.
They are eight points from the safety zone, having scored the fewest goals while they also have the league's worst defence.
Pereira's departure ends an 11-month spell in charge after he joined in December 2024, replacing Gary O'Neil with Wolves languishing in 19th place.
The Portuguese coach led them to safety with a run of six straight wins in March and April, finishing 17 points clear of the relegation zone.
Despite a poor start to the current campaign, club chairman Jeff Shi had publicly backed Pereira earlier this season, rewarding him with a new contract after last season's turnaround.
Pereira's exit marks his sixth straight year leaving a managerial post.
The Portuguese has had short-lived spells across five countries since 2020, managing Shanghai SIPG, Fenerbahce, Corinthians, Flamengo and Al Shabab before joining Wolves.
Check out the match report from Saturday's game with Flashscore.