Sarries lock in England star
Lozowski, who joined Saracens from Wasps in 2016, has signed a two-year deal that will keep him at the club through to 2020.
The 24-year-old played an important role in the team's Champions Cup defence last season and continues to impress as part of Saracens' exciting backline.
During the offseason, he earned his first England cap in June against Argentina.
"It's great to be part of this team and I'm delighted to have re-signed," Lozowski said.
"I've really benefitted from being in the environment and from being around good players and good coaches. I wake up in the morning and look forward to coming to training."
Saracens director of rugby Mark McCall added: "We're delighted that Alex has agreed on a new-deal. Alex will have an important role to play for us as he continues to develop as a player, so naturally we're very happy to announce that he'll be staying at Allianz Park until at least 2020.
"In his brief time at the Club, Alex has already shown how good a player he is, but the most exciting thing for us is how much improvement we believe there is to come from him alongside our core of young, hungry, homegrown players. We're very excited that he'll be continuing his exciting career with Saracens."
The move comes shortly after Saracens' other fly-halves – England's Owen Farrell and academy graduate Max Malins – both signed new deals and secures the future of three of the country's most promising and leading playmakers to the north London club.
Saracens also recently resigned England hooker Jamie George and lock Nick Isiekwe and continue to put an emphasis on developing English talent.
On being part of the group, Lozowski said: "I think being surrounded by the calibre of guys that we've got here is only going to bring your game up. I'm really grateful to be part of this team.
"There is a lot of laughter around the place every day, we try and have a good time. Then when it gets time to get down to serious business we all tune in and get on with the work. That's a nice balance to have."
