Asisat Oshoala struck a hat-trick, Ana-Maria Crnogorcevic scored two, Mariona Caldentey was also on target and 16-year-old Vicky Lopez scored her first goal for the club as Barcelona reached the landmark.
Barca have won all 15 of their league games this term after completing a perfect season last time out, winning all 30 of their fixtures.
It is the first time that a team has won 50 straight games in a professional league, according to FIFA.
They last lost in the Spanish league on June 1, 2021, when they were beaten 3-2 by Atletico Madrid. They were forced to field a weakened side in that match having played the final of the Copa de la Reina just 48 hours earlier.
That defeat to Atletico sparked a 40-game winning run across all competitions which ended when they lost the second leg of their Champions League semifinal to Wolfsburg in April 2022.
However, Barca have remained unbeaten domestically and Real Madrid became the first side since Atletico in June 2021 to stop them from winning in 90 minutes last week when they held them to a 1-1 draw in the Super Cup semifinal. Barca, despite having a player sent off, won 3-1 after extra time.
In total, Barca's unbeaten run in all Spanish competitions would now stand at 59 games after the win over Levante Las Planas, although one of those results has now been overturned.
The 9-0 win against Osasuna in the Copa de la Reina earlier this month has since been awarded to Osasuna after Barca fielded an ineligible player in the game.
The Royal Spanish Football Federation announced on Tuesday that due to the participation of Geyse Ferreira -- who was sent off in the competition last season for Madrid CFF and due to serve a suspension -- Barca would be expelled from the competition. The Catalan club are appealing the decision.
According to UEFA, the longest men's domestic league winning streak in European football is held by Benfica, who won 29 games in a row between 1971 and 1973.
Data for the women's game is more difficult to verify due to the lack of a professional structure until fairly recently.
However, both Arsenal and Lyon have registered long runs without losing in the 21st century. Arsenal were unbeaten in 108 league games between 2003 and 2009 -- including a 51-game winning streak at one point -- though the league was not fully professional at the time.
Lyon's unbeaten run stretched 80 matches between 2016 and 2020 but they did not register 50 wins in a row during that stretch.