Fernandes took to social media to post a tribute to Ten Hag just an hour after his dismissal was confirmed in an official club statement.
United's dismal 2-1 defeat by West Ham on Sunday proved to be the final straw with the patience of senior figures at Old Trafford snapping.
Mail Sport understands the squad were informed of Ten Hag's axing at the same time as the public announcement and Fernandes was the first to react.
'Thanks for everything boss!' he wrote on Instagram. 'I appreciate the trust and the moments we share together, I wish you all the best in the future.
Bruno Fernandes has broken his silence on Erik ten Hag's sacking at Manchester United
'Even knowing the last period isn't [sic] been great from all of us I hope you fans can keep with you the good things the manager has done for our club!'
United are 14th after a stuttering start to the Premier League campaign and three consecutive draws in the Europa League further piled the pressure on Ten Hag.
Ten Hag was informed of his dismissal on Monday morning and has departed after two and a half years in charge. He won the Carabao Cup and FA Cup.
Ruud van Nistelrooy, the club legend hired as part of Ten Hag's new-look backroom staff in the summer, has been placed in interim charge in the short term.
United's search for a permanent replacement is already underway and Mail Sport has reported that the club have already spoken to several potential candidates.
Talks were held with former Barcelona head coach Xavi while the likes of Ruben Amorim, Edin Terzic and Thomas Frank hold admirers at Old Trafford.
A club statement confirming Ten Hag's sacking read: 'Erik ten Hag has left his role as Manchester United men's first-team manager.
'Erik was appointed in April 2022 and led the club to two domestic trophies, winning the Carabao Cup in 2023 and the FA Cup in 2024.
'We are grateful to Erik for everything he has done during his time with us and wish him well for the future.'