EFL Championship side Rotherham United have completed the signing of ex-Nigeria U20 international Semi Ajayi on a permanent deal from Cardiff City.<br /><br />The central defender, who initially joined the Millers on loan until the end of the season, has penned a contract that will see him remain at S60 1AH until June 30, 2020, subject to FA, EFL and international clearance.<br /><br />Ajayi began his career with Charlton Athletic, but did not make a first-team appearance for the Addicks before his departure in 2013.<br /><br />He then had spells with Arsenal, Cardiff City, AFC Wimbledon and Crewe Alexandra .<br /><br />He has featured nine times for Rotherham United since his arrival in January, and was on target against Huddersfield Town on February 14.<br /><br />Ifeanyi Emmanuel <br />