The 24-date tour will get under way Oslo on March 18 and wrap up in Leeds on April 14.
Mono will be playing in support of their 2019 album Nowhere Now Here, while Williams will be playing tracks from her new album Forever Blue, which was released earlier this month.
Speaking about the tour, Mono guitarist Taka says: “We're excited to be able to return and give you live music again after almost a year-long unfortunate global health crisis.
“Through the real loud live experience, we hope to re-connect, share hope and rejoice again with you all.”
Tickets for the tour will be available from tomorrow (July 17) through Mono’s official website.
Mono 2021UK and European tour with A.A. Williams
Mar 18: Oslo Jakob, Norway
Mar 19: Stockholm Sodra Teatern, Sweden
Mar 20: Copenhagen Pumpehuset, Denmark
Mar 21: Hamburg Uebel & Gefahrlich, Germany
Mar 22: Berlin Columbia Theater, Germany
Mar 23: Cologne Luxor, Germany
Mar 24: Zurich Mascotte, Switzerland
Mar 25: Bulle Ebolition, Switzerland
Mar 26: Toulouse Le Rex, France
Mar 27: Biarritz Atabal, France
Mar 29: Porto Hard Club, Portugal
Mar 30: Lisbon LAV, Portugal
Mar 31: Seville Custom, Spain
Apr 01: Murcia Garaj, Spain
Apr 02: Madrid Cats, Spain
Apr 03: Barcelona Apolo 2, Spain
Apr 05: Besancon L'Antonnoir, France
Apr 06: Paris Trabendo, France
Apr 07: Antwerp Zappa, Belgium
Apr 08: Lille Aeronef, France
Apr 10: London Lafayette, UK
Apr 11: London, Earth, UK
Apr 13: Glasgow Oran Mor, UK
Apr 14: Leeds City Varieties, UK