Back row giant Senatore, who can play at flanker or No 8, is considered one of the most exciting talents in Argentinean rugby having already won 17 caps for his country.
The abrasive 28-year-old impressed at the 2011 Rugby World Cup before enjoying a spell in the Top 14 in France with Toulon, making three European appearances for the club. He last played for Argentina against Ireland at Lansdowne Road in November.
"Leonardo is a fantastic signing for Warriors," said head coach Richard Hill. "Like the vast majority of Argentinean players he is very passionate about his rugby, will give everything, is very dedicated and extremely loyal.
"He has good technical ability and is a strong ball-carrying back row forward of considerable size. Leonardo is a real athlete who brings vast experience from his international action.
"We have seen him in action for Argentina and in the World Cup. He has been on our radar for the last few years and he has been in fantastic form.
"He will add experience and quality to our squad and we look forward to him joining."
And they have also announced that full back Chris Pennell has also put pen to paper on a new contract at Sixways.
Full back Pennell, a home-grown product of the Warriors Academy, has been one of the star performers at Sixways over the last five years and produced some of his best displays this season.
"When I first joined Worcester Warriors I was told that Chris was the future of the club - that very much remains the case today," said Hill.
"His attitude and work ethic is superb and he has really developed himself as a player."