The England international has signed on for another three-and-a-half years with the Premiership club.
England captain Owen Farrell has had surgery on an injured thumb just two weeks before their Six Nations opener with champions Ireland in Dublin but is still expected to be fit to play.
The Chiefs moved top with a dominant 31-13 victory over their rivals at Sandy Park.
Maro Itoje is expected to be fit for the start of the Six Nations in February after Saracens' director of rugby Mark McCall said the England forward does not need surgery to repair a knee injury.
England centre Alex Lozowski has been banned for a further two weeks following a European Rugby disciplinary hearing in London on Wednesday.
Saracens hooker Christopher Tolofua has singed a three-year deal with Toulon, the French club announced on Monday.
Alex Lozowski will miss England's opening autumn international against South Africa after his two week ban was extended.
Alex Lozowski will be free to play in England's autumn international fixtures next month after he was only hit with a two-week ban by a European Rugby disciplinary panel.
England will be without Billy Vunipola for the autumn internationals after he fractured his arm in Saracens' win over Glasgow Warriors at the weekend.
Billy and Mako Vunipola both went off injured in Saracens' victory over Glasgow on Sunday, putting their participation in England's Autumn internationals in doubt.
Brian O'Driscoll has tipped Exeter Chiefs as favourites to win the Champions Cup title this season, alongside recent winners Leinster and Saracens.
Saracens and Exeter Chiefs' blistering start to the Premiership season shows they are ahead of the rest of the division, according to Worcester's Alan Solomons.
Richard Wigglesworth broke the all-time Premiership appearance record in Saracens' home victory over Gloucester on Sunday.
England and Sale Sharks wing Chris Ashton could face further disciplinary action after he was sent off in a pre-season friendly in France.
England internationals Mako and Billy Vunipola have extended their contracts with Premiership champions Saracens until 2022.
The former Saracens hooker, who was in South Africa on holiday, won the last of his 10 Test caps at the 2015 Rugby World Cup and attended the first Test against England at Ellis Park as a fan.
Leinster and Saracens fans were smiling this weekend as domestic honours were secured, while Castres set up a mouthwatering Top 14 final in Paris next weekend.
It has been a season of highs and lows for Saracens, but they have finished it off in style.
Exeter and Saracens bring down the curtain on another thrilling Aviva Premiership season, and a couple of storied careers, when they meet at Twickenham on Sunday.
James Harrington runs the rule over the Aviva Premiership and PRO14 finals, plus the Top 14 semifinals, to predict which player will shine brightest, who will have an afternoon to forget and a whole lot more.
Billy Vunipola is expected to start Saracens' Aviva Premiership final against Exeter at Twickenham on Saturday despite coming off at halftime in Saracens' semifinal victory over Wasps.
Saracens would be reluctant to lose Alex Sanderson to England after Mark McCall revealed he is seen as his eventual successor as the club's director of rugby.
Plenty was sorted out over an enthralling few days but who shone, who had a weekend to forget and what will fans be talking about ahead of a busy period of domestic action?
Following eight months of intense competition four teams are left battling for silverware in the Aviva Premiership and PRO14, while Castres, Lyon, Toulon and Toulouse target a place in the Top 14 semifinals.
The 2017-18 Aviva Premiership semifinals take place with Newcastle looking to emulate champions Exeter by beating the Chiefs and punching their ticket to Twickenham.
- SARAC3rdTRIES SCORED 1st Leinster : 27 Tries ScoredLEINS1st2327
- SARAC2ndPOINTS DIFFERENCE 1st Leinster : 116 Points DifferenceLEINS1st104116