Matthew James Cassidy, 19, from Merseyside, died at Bethel Place in Connah's Quay, on 29 May.
The woman, 19, and from Connah's Quay, was arrested on Wednesday on suspicion of conspiracy to commit murder.
A 19-year-old man from Liverpool has already been charged with Mr Cassidy's murder and has been remanded in custody.
Police officers are continuing to search properties in the area following the latest arrest.
A woman has been arrested by police investigating the fatal stabbing of a man in Flintshire.