The former Liverpool and Tottenham Hotspur midfielder has been impressed with the impact that Ighalo has made at United since his move to Old Trafford in January.
Ighalo joined the Red Devils on loan from Chinese outfit Shanghai Greenland Shenhua in the January transfer window until the end of the season.
The former Watford and Changchun Yatai striker has scored one goal in two Europa League games for the Red Devils and has played 59 minutes in the Premier League, according to WhoScored.
Redknapp told Sky Sports about Ighalo: “Brilliant signing.