Cullen, a forward who played 21 seasons in the NHL, is 136 days older than the defenseman, who turned 42 on March 18.
"It's hard to believe I'm now the oldest active player in the NHL," Chara wrote on Instagram on Thursday. "It's been a long time since my rookie season but this game always keeps me young. Having the opportunity to play in the League all these years with and against the best players in the world has taught me time and time again that it's a humbling game and age is just a number."
The next oldest active player is Anaheim Ducks goalie Ryan Miller, who turns 39 on July 17.
Joe Thornton, a forward who turned 40 on July 2, is older than Miller but is an unsigned free agent, as are forwards Patrick Marleau (40 on Sept. 15) and Chris Kunitz (40 on Sept. 26).
Florida Panthers goalie Roberto Luongo was 40 years old when he retired June 26.
Cullen had been the oldest active player since Jan. 29, 2018, when Calgary Flames forward Jaromir Jagr was assigned to Kladno in the Czech Republic. Jagr was 17 days from his 46th birthday at the time; Cullen turned 41 almost three months prior (Nov. 2).
Chara signed a one-year contract March 23 to return for a 22nd NHL season. He is recovering from a fractured jaw sustained in Game 4 of the Stanley Cup Final against the St. Louis Blues but said after that series he expected to be ready for training camp. He also had an MRI for a lower-body injury sustained during the Stanley Cup Playoffs and missed 16 games during the season with a tear in his left MCL.
"I definitely was able to push my body to different limits, which I kind of heard they exist but was never in that position that I had to push it," Chara said June 14. "Definitely this postseason ... it was one of those that kept pushing and pushing it and find another level of limits that you can go through and beyond."
Instagram from @zeechara33: It's hard to believe I'm now the oldest active player in the NHL. It's been a long time since my rookie season but this game always keeps me young. Having the opportunity to play in the league all these years with and against the best players in the world has taught me time and time again that it's a humbling game and age is just a number! ------------------------ Je ťažké tomu uveriť že momentálne som najstarším aktívnym hráčom v NHL. Je to už dávno od mojej prvej sezóny, ale stále sa cítim mladý. Mám možnosť hrať v NHL s a proti najlepším hráčom sveta čo ma zároveň naučilo dve veci. Byt skromný a vďačný a to že vek je iba tvoje myslené číslo.
Selected by the New York Islanders in the third round (No. 56) of the 1996 NHL Draft, Chara has 642 points (200 goals, 442 assists) in 1,485 NHL games with the Bruins, Islanders and Ottawa Senators.
He won the Norris Trophy voted as the best defenseman in the NHL in 2008-09, has been selected to play in five NHL All-Star Games, helped Boston win the Stanley Cup in 2011, and is the longest-tenured captain in the NHL (since 2006-07).
"I enjoy my role," Chara said after signing his latest contract. "I really take a lot of pride in being a captain and being one of those mentor guys that we try to help younger guys to lead them in the right direction and make sure they keep getting better and better.
"It's just like I said, a lot of fun to be part of. And I think that with the future, this team is in the right place so I for sure want to be part of it and still contribute with the experiences that I have now."
