"The nice thing about Nicky is that he gives us options. He can play anywhere along the right side," said Worthington.
"I would like to have signed him 15 months ago, but obviously the lure of the Premiership, and rightly so for the boy, was more appealing so he went to Bolton".
"He's been heavily involved at Bolton and we have the opportunity of bringing him out and adding to what we have got."
Southall is expected to go straight into the Canaries squad that face Preston on Saturday.