Vale have made a poor start to the new season, winning just one of their opening eight League Two games to sit bottom of the entire Football League.
Brown took over as manager on an interim basis last December and was handed the reins permanently during the summer despite the club suffering relegation from League One.
Now, with the possibility of a second consecutive relegation looming - this time out of the Football League - Vale have chosen to part company with Brown, leaving David Kelly and Chris Morgan to take charge of the team until a successor is found.
Port Vale CEO Colin Garlick told the club's official website: "We are all very disappointed with the start to the season, I know Michael and his staff have worked extremely hard to try and rebuild the club and achieve the results that we were looking for but unfortunately, this has not happened. I would like to thank Michael for his hard work and wish him and his family all the very best for the future".
Kelly and Morgan's first game in charge will come against Yeovil Town at Huish Park next weekend.