The export business was affected by World War I, for example the Löwenbräu London Depot closed for the duration, making its employees redundant.
In 1921, Löwenbräu merged with Unionsbräu Schülein & Cie and Munich Bürgerbräu, two other breweries.
By Brey's order in 18, the Rank brothers built the Löwenbräukeller, according to the plans of Albert Schmidt on the brewery's property.
The grand opening of the Löwenbräukeller was on 14 June 1883. Around the turn of the century, Löwenbräu was the largest brewery in Germany, though strongly dependent on exports.
The brewery was formally incorporated in 1872 under the name Aktienbrauerei zum Löwenbräu.