The shows were originally set to get under way in April this year, but with the coronavirus pandemic causing chaos in the live music scene, both bands decided to move the shows to September and October.
However, with restrictions on mass gatherings and travel limitations still in place in both the UK and mainland Europe, the entire tour has now been moved to September and October 2021.
Evanescence vocalist Amy Lee says: “We are so disappointed that we won't be seeing you this fall, but we're accepting the challenge 2020 is giving us and pouring our time and hearts into making a great album instead.
"Friends, we miss you terribly and can't wait to play these songs for you next year. Be safe, be well, we love you!”
Within Temptation singer Sharon Den Adel adds: “We know this year will not be easy for you and we will do whatever it takes to get you through by continuing to write and release new songs.
“Knowing that we won’t get to play for you this year is hard for everyone, but everyone’s health and wellbeing is our number one priority. Whatever happens, this tour will happen! We can’t wait to see you again in 2021. For now, stay safe.”
All previously purchased tickets and VIP packages will remain valid for the rescheduled dates, while those seeking refunds should contact their point of purchase.
Evanescence have been working on their new studio album titled The Bitter Truth and released their new single Wasted On You back in April. Within Temptation, meanwhile, launched the new track Entertain You in May.
Evanescence and Within Temptation 2021 Worlds Collide European dates
Sep 08: Zurich Hallenstadion, Switzerland
Sep 09: Milan Mediolanum Forum, Italy
Sep 11: Berlin Velodrom, Germany
Sep 12: Gliwice Arena, Poland
Sep 14: Leipzig Quarterback Immobilien Arena, Germany
Sep 15: Hamburg Barclaycard Arena, Germany
Sep 17: Amsterdam Ziggo Dome, Netherlands
Sep 18: Amsterdam Ziggo Dome, Netherlands
Sep 20: Paris Accorhotels Arena, France
Sep 21: Düsseldorf Mitsubishi Electric Halle, Germany
Sep 22: Munich Zenith, German
Sep 24: Esch-Sur-Alzette Rockhal, Luxembourg
Sep 26: Frankfurt Festhalle, Germany
Sep 27: Brussels Palais 12, Belgium
Sep 28: Brussels Palais 12, Belgium
Sep 30: Glasgow SSE Hydro Arena, UK
Oct 01: Leeds First Direct Arena, UK
Oct 03: Birmingham Utilita Arena, UK
Oct 04: London The O2, UK
Oct 07: Madrid Palacio Vistalegre, Spain (Evanescence only)