The 23-year-old has been capped four times by Northern Ireland including World Cup qualifying matches against Croatia, Iceland and France in 2009-10.
Recently at Loughborough University, Avilla is now ready to step into club football again and has joined the Spurs squad ahead of the FA Women's Premier League campaign, which kicks-off against Gillingham on August 24.
"It's another great signing and I'm sure Avilla will be a real asset for the club," said Spurs Ladies manager, Karen Hills.
"She's working hard to return to full fitness and she showed real touches of class in the friendly against Arsenal at the weekend.
"She plays anywhere across the front three, works hard and understands the game. She looked a quality player against Arsenal."
The ladies lost 5-3 against the Gunners on Saturday - pre-season latest and more photographs to follow on Thursday.