The singer-songwriter - currently top of the Official UK Charts - will top the bill on August 14.
We Were Promised Jetpacks, The Lightening Seeds and Madness have all also been added to the bill.
They join a stellar list of artists already announced including Florence and the Machine, James, Primal Scream and Johnny Marr.
The Edinburgh Summer Sessions stretch across eight days of live music with Edinburgh Castle providing the backdrop to the festival site at the Ross Bandstand.
Capaldi said: “Well, well, well. Look who’s playing a big outdoor show in Edinburgh this summer.”
The man of the moment is making his Summer Sessions festival debut and a much-welcomed return to Scottish soil after a whirlwind year for the young Bathgate-born singer. Currently top of the Official UK Charts with his tune ‘Someone You Loved’, Lewis Capaldi has gone from strength to strength since first appearing at Glasgow’s TRNSMT Festival back in 2017.
Scottish outfit We Were Promised Jetpacks have a cult following and are a welcomed addition to the CHVRCHES date on 11th August. Releasing three albums in five years, the band will bring big tunes and singalongs to the all-Scottish bill. Also added today are The Lightning Seeds, joining Madness on 18th August.
We Were Promised Jetpacks said: “We’re very excited to be playing alongside CHVRCHES under the castle in our hometown. It’s been great watching a local band grow into the international stars they are today and we’re looking forward to sharing the stage with them.”
Ian Broudie, from The Lightning Seeds said: “We are delighted to join the brilliant Madness at Edinburgh Summer Sessions this year. We have heard great things about the new festival and can’t wait to play to that famous Scottish crowd in the mighty Edinburgh capital!”
Tickets are on sale from 9am on Friday from www.smmrsessions.com.
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