Wilkinson's career has been blighted by a catalogue of injuries since he dropped the goal which won England the World Cup in 2003.
The 27-year-old has not played for his country since and has barely put together a decent run of games for Newcastle after being struck down by neck, bicep, knee and groin injuries.
Wilkinson was forced to re-evaluate his approach to the sport after realising his famously intensive preparations were at least partly to blame for the injury problems.
And at the start of a season which culminates in England's World Cup defence, Fletcher believes Wilkinson is ready to take on all-comers once again.
"He's like a new signing for us," said Fletcher, who replaced Rob Andrew as director of rugby last Friday.
"Training has gone really well for him, and I think he's a better player now.
"Having him back with a run of games under his belt is an exciting prospect for everyone concerned with the club."
Wilkinson has not played regular top-class rugby in three seasons but he was backed to make an emphatic return to the scene by Andrew Mehrtens, the former New Zealand fly-half.
"It is certainly not anything that is too tough for Jonny Wilkinson," said Mehrtens, the Harlequins fly-half.
"He is a talented rugby player. He has been in the English team since he was 18. He is only coming into his best years now.
"For a fly-half your best years are late 20s and early 30s.
"Once you have been out of it for a while it takes a bit of time to get used to the speed of the game and the sharpness. But he is well up to it. The more he plays he will get better and better."