Both players made their debuts in the 1-1 draw against Newcastle Town on Monday night.
Nield, 23, joins from Northwich Victoria having only signed for them from Witton Albion in the summer.
He has previously played for Chester, AFC Liverpool and Airbus UK.
Ready, 22, joins from Marine having come through the junior ranks at Blackpool.
Meanwhile, Rainford makes the move to EVO-STIK West Division rivals Clitheroe, having scored twice in 10 games since joining Widnes in the summer.
A club statement said: "Everyone at the club would like to thank Jamie for his efforts at the club, and would like to wish him well for the future.”
Widnes are in league action on Saturday when they make the trip to Skelmersdale United.