MacKenzie, 29, joined City on Deadline Day this Monday on a loan deal that will keep him at the Coral Windows Stadium until the end of the season.
The deal, which is subject to Football Association and Football League clearance, should now see MacKenzie in City's squad for this Saturday's trip to Port Vale.
The Scotsman becomes the second Blackpool player to join the Bantams on loan this season following the arrival of forward Francois Zoko back in November.
The Lanark-born centre half started his career at Glasgow Rangers back in 2004. MacKenzie also spent four seasons with Dundee during his time in his native Scotland.
MacKenzie made the move south of the border to play for Milton Keynes Dons in 2010. After three years with the Dons, MacKenzie joined Blackpool.
MacKenzie - a former skipper at Blackpool - has made 47 appearances in the Championship for the Seasiders following his move from stadiummk back in March 2013.
The defender also has experience of two and a half seasons at League 1 level with MK Dons. MacKenzie featured in the Play-Offs in successive seasons for the Dons (2010/2011 and 2011/2012) during his time in Milton Keynes.