Ardley, 32, joins for free from Watford. He's a former Wimbledon player with Premiership experience.
He has been playing regular football with Watford and is the "battle hardended" player that Lennie said he was looking for yesterday.
Lawrence has not ruled out a second signing and has said no players will leave.
"Neil can play wide right, wide left and, at a pinch, full-back," Lawrence told Wednesday's Echo.
"He's a good lad, a good leader and a good type. We tried to get him out at Christmas, but Watford didn't want to know at the time.
"We have one player in and that's good news. There is a slight possibility of another signing, on loan, but there will not be anybody going out."
Ardley has played over 380 league and cup games and has made 38 appearances this season including the league cup semi final matches against Liverpool.
Good luck and welcome to Neal and let's hope he can make a difference to the City midfield that recently lost both Graham Kavanagh and Inamoto.