The musician, 28, has been added to the bill which includes Queen + Adam Lambert who will open the concert, while Diana Ross will close the event, marking her first UK live performance in some 15 years.
Ms Banks said: “I’m super excited to be a part of this legendary line-up, it’s going to be an amazing night”.
Other famous faces from the worlds of sport, stage and screen who are part of the event include Sir David Attenborough, tennis star Emma Raducanu, David Beckham, Stephen Fry and Dame Julie Andrews, with the evening also featuring a specially recorded performance from Sir Elton John.
Supremes singer Ross previously said of the event: “I have had the honour of meeting the Queen many times throughout my life, including when I was with my family.
“Her Majesty has, and continues to be, such an incredible inspiration to so many across the world and I was absolutely delighted to receive an invitation to perform on such a momentous and historic occasion.”
Her performance on June 4 comes ahead of her playing the Glastonbury Festival legends slot on June 26 on the acclaimed Pyramid Stage.
The main concert airs from 8pm on BBC One, iPlayer and BBC Radio 2 on June 4.