Marina Granovskaia was among the Stamford Bridge crowd during Chelsea's 2-1 win over Newcastle United on Sunday.
The Russian-Canadian business executive had not attended a Chelsea game since she left her role as the club's chief executive in June 2022.
Granovskaia was a director at Chelsea for eight years before she left 28 months ago, shortly after Todd Boehly had bought the club from Roman Abramovich.
She also worked as Abramovich's chief assistant for over a decade.
During her time on the Chelsea payroll, Granovskaia - who was famous for playing a key role in the club's transfer dealings - watched games from the executive box at Stamford Bridge.
But she was in with the regular punters on Sunday.
Granovskaia documented her day out by sharing multiple photos via Instagram alongside the words: 'First time in with the supporters at Stamford Bridge and, no, I was not tall enough to see the goals! But wonderful to be back to witness such a great performance and important win!'
Nicolas Jackson and Cole Palmer were Chelsea's scorers on Sunday, with their strikes coming either side of a goal by Newcastle's Alexander Isak.
The result saw Chelsea end the weekend fifth in the Premier League table.
Granovskaia had taken to Instagram earlier in the week to wish Abramovich a happy 58th birthday.
On Thursday, she shared an old photo of herself together with Chelsea's former owner.
The photo was accompanied by the caption: 'Considering how many messages sent to this page refer to Roman, I thought it would be right to wish him a very happy birthday on here (you never know, he might be reading!).
'Roman was a big part of my life from 1997 until 2022 and I know he touched the lives of many of you, so I have a feeling there will be many congratulatory messages under here… Happy Birthday Roman!'
Abramovich was the man in charge at Chelsea from 2003 until 2022.
His sale of Chelsea came after the Premier League disqualified him as a director of the club amid allegations he was an ally of Russian president Vladimir Putin, who had recently invaded Ukraine.
Since Abramovich left Chelsea, the new ownership have employed six different managers.
Sunday's win over Newcastle was current manager Enzo Maresca's 14th game in the job.
After the game, Chelsea manager Enzo Maresca was seen blowing kisses towards the crowd
Speaking after the game, Maresca told BBC Sport: 'Overall, I was very happy with everything but especially the way we worked off the ball and pressed together. We fought together.'
On how Chelsea are doing in the Premier League table, he added: 'I said many times that the club never mentioned about top four. They just mentioned to try to build something important. We will see.'