However, after less than a full season at the Bescot, the one-time Northern Ireland international had his contract paid up by the Saddlers.
A free agent, 31-year-old Sonner is now hoping to kick-start his career at the City Ground having signed a one year contract with Forest.
"Danny will add depth to our choices in midfield and at 31 he knows the game inside out," said Forest boss Paul Hart.
DANNY SONNER RECENT CAREER HISTORY
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