Pietrangelo's contract carries a full no-movement clause, according to TSN's Pierre LeBrun.
The 30-year-old was considered the top UFA on the open market. He finished fourth in Norris Trophy voting last season after racking up 52 points in 70 games with the St. Louis Blues.
Since becoming a full-time NHLer in 2010-11, Pietrangelo has averaged 50 points per 82 games. He's been durable, too, playing at least 70 contests per season (excluding the shortened 2012-13 campaign).
The 6-foot-3 rearguard is also a proven winner. He captained the Blues to a Stanley Cup in 2019, won an Olympic gold medal with Team Canada in 2014, a World Cup title in 2016, and a world junior gold in 2009.
The Blues offered Pietrangelo an eight-year deal with an $8-million cap hit prior to free agency, according to The Athletic's Jeremy Rutherford. St. Louis pivoted to Torey Krug once free agency opened, signing the former Boston Bruins defenseman for seven years with a $6.5-million AAV.
The Golden Knights' front office has been aggressive pursuing available high-end players since the franchise joined the league. Since the 2018 offseason, the team has landed Max Pacioretty, Mark Stone, and Robin Lehner via trade, and signed them all to long-term extensions. They were also reportedly in the Karlsson sweepstakes before the San Jose Sharks landed the former Norris winner.