Matalan workers Zoe Morgan, 21, and Lee Simmons, 33, were found dead near the Queen Street store on Wednesday.
Andrew Saunders, 20, of no fixed abode, was later arrested, and then charged on Thursday.
He spoke only to confirm his name, age and address at Cardiff Magistrates' Court on Friday.
The defendant was remanded in custody to next appear before Cardiff Crown Court on Monday.
In a tribute released on Thursday, Miss Morgan's family described her as a "beautiful daughter, sister, granddaughter and auntie who had a heart of gold and would do anything for anybody".
The statement continued: "She was taken away from us tragically, too soon, and has left a massive hole in our lives that will never be filled.
"Zoe will always be in our hearts forever and always. We are all broken hearted. xx"
The Matalan store remained closed for a second day on Thursday but reopened on Friday.
A man charged with the murder of a couple found stabbed on a main Cardiff shopping street near their workplace has appeared in court.