The Poland captain scored a remarkable seven goals in three league matches in October.
He started the month with a hat-trick in under 30 minutes against Alaves (3:0). He then went on to bag a brace in a 5:1 thumping of Seville.
He also scored a double, with two precise finishes against Barca’s arch rivals Real Madrid, in Spain's most prestigious match, El Clasico.
"I am truly grateful for this distinction, heartfelt thanks to everyone who supported me - my family, friends and fans - you motivate me to work harder every day. I raise a toast to continuing this journey together. Let's create memories," Lewandowski wrote on Instagram.
This is the third occasion the 36-year-old has taken the award since arriving in Spain in the summer of 2022. He previously won it in October 2022 and in February this year.
League leaders Barcelona have had a dominant start to the season but really raised the level in October. Their form was reflected in La Liga’s other awards for the month. Barca’s Hansi Flick was named best coach, while midfielder Pedri received the award for best under-23 player.
Lewandowski has scored 17 goals in all competitions for the club this season. He not only tops the chart in La Liga but is also the leader of the European Golden Boot, with his 14 league goals equating to 28 points.