The 19-year-old, who can play on both wings as well as up front, arrives on a deal until the end of the season, with the option of a further year, after leaving Arsenal by mutual consent earlier this week.
Jeffrey trained with his new team-mates for the first time on Thursday and is available for Saturday's fixture at Mansfield Town, subject to Football League approval.
After joining the Gunners at the tender age of eight, he progressed through the ranks at the Premier League giants, impressing right the way up to U21 level.
Jeffrey made his senior debut during a loan spell with League 1 side Stevenage in the closing stages of last season, while he found the net six times in just seven appearances on loan at Boreham Wood recently.
“He’s an Arsenal player so it’s a good coup for us,” Ainsworth told wwfc.com. “He’s got pace, is very direct and can score a goal.
“One thing we’ve been lacking this season is goals and I’ve brought in someone who I believe can help us in that department.”
Ainsworth added: “It’s been a bit of a patient one. U21s football is different to League 2 and we’ve had to make a decision as to whether he can handle it.
“The physicality, the directness, the pitches - it’s totally different to where he’s been, but we feel he’s got all the attributes to be a good player.”
Anthony will wear the number 15 shirt.