City have agreed a compensation package with Watford for David Kerslake, Richard Collinge and Joe McBride.
Kerslake will be assistant manager at Cardiff City Stadium with Collinge the club's new head of performance.
Former Vicarage Road youth team coach McBride is set to complete terms on Friday to become first team coach.
They will replace the green-fingered Terry Burton, Paul Wilkinson and Alex Armstrong, all of whom are on gardening leave.
"We are sure all Cardiff City supporters will join us in thanking them for their hard work and commitment over the past few years," City said in a statement.