Cardiff have signed Scotland striker Ross McCormack from Motherwell and defender Darren Dennehy from Everton.
McCormack, 21, was a target for Wigan and Middlesbrough in January but has opted to join the Bluebirds after reaching the end of his contract.
Dennehy, 19, was offered new terms by Everton but chose to move on.
Cardiff full-back Kevin McNaughton, who played when McCormack made his Scotland debut against Czech Republic on 30 May, has agreed a new three-year deal.
"This is further evidence that we are putting together a squad that can compete to gain promotion to the Premier League," said Cardiff chairman Peter Risdale.
Republic of Ireland Under-21 international Dennehy graduated from the Goodison Park academy and can play at centre-back and in midfield.
McCormack started his senior career with Rangers and hit the headlines when he scored in a 1-1 Champions League draw away to Porto.
But he was loaned out to Doncaster later that season and left Ibrox in 2006 after making just 14 appearances for the Ibrox club.
McCormack's first season with Motherwell was plagued by injury and he scored just three times in 15 appearances.
However, he enjoyed an impressive campaign last season, finding the net 11 times.
McNaughton arrived at Ninian Park from Aberdeen two years ago and was one of Cardiff's most consistent performers last season.
McCormack, 21, was a target for Wigan and Middlesbrough in January but has opted to join the Bluebirds after reaching the end of his contract.
Dennehy, 19, was offered new terms by Everton but chose to move on.
Cardiff full-back Kevin McNaughton, who played when McCormack made his Scotland debut against Czech Republic on 30 May, has agreed a new three-year deal.
"This is further evidence that we are putting together a squad that can compete to gain promotion to the Premier League," said Cardiff chairman Peter Risdale.
Republic of Ireland Under-21 international Dennehy graduated from the Goodison Park academy and can play at centre-back and in midfield.
McCormack started his senior career with Rangers and hit the headlines when he scored in a 1-1 Champions League draw away to Porto.
But he was loaned out to Doncaster later that season and left Ibrox in 2006 after making just 14 appearances for the Ibrox club.
McCormack's first season with Motherwell was plagued by injury and he scored just three times in 15 appearances.
However, he enjoyed an impressive campaign last season, finding the net 11 times.
McNaughton arrived at Ninian Park from Aberdeen two years ago and was one of Cardiff's most consistent performers last season.