The 'On The Floor' hitmaker's partner took to Instagram to share a black and white clip composed of images of him with Jennifer and each of their children, including the singer's 11-year-old twins Max and Emme - whom she has with ex-husband Marc Anthony - and the retired baseball ace's daughters Ella, 11, and Natasha, 14, whom he has with ex-spouse Cynthia Scurtis.
He captioned the video, which was soundtracked by Billy Joel's 'This Is The Time' : ''#HappyBirthdayJLO
It's your party, Jennifer!
Thank you for inviting all of us to share this special day with you. (sic)''
An emotional Jennifer commented: ''I'm crying....I love our life...I love you so much... thank you my beautiful Macho... (sic)''
The 'Second Act' actress has been celebrating her milestone birthday all summer on the 'It's My Party Tour', and she has admitted that she doesn't feel her age.
She said: ''It's nuts. Anybody else still feel like you're 16? I feel like I'm 26.''
As for her plans for her birthday, the 'I'm Real' singer just wants to ''lay with [her] feet up''.
Jennifer has today off from her tour and didn't want Alex to plan anything in particular as she'd rather rest then have a joint party on his birthday, which falls on the same day as her final concert.
She said: ''Well my [50th] birthday is the 24th [of July]. His is the 27th. We close the tour in Miami the 25th, 26th and 27th, so I have off on my birthday but I have to do three shows in a row in Miami, and the last one is on his birthday.
''We'll probably have a party that night, then I head off to Europe.
''On my birthday, I probably would be like, 'Let me lay here with my feet up.' That would be the best birthday present before I have to kill three shows in Miami.''
What's new in the music world this week?
'Sounds of Silence' was released on this day (January 17th) in 1966.
Listen to Alex Bayly performing 'Animal'.
Two weeks ahead of Independent Venue Week, Dry Cleaning made 'Britain's Best Small Venue 2015' (NME) the second port of call on their 2020 tour.
'Leave Home' was released on this day (January 10th) in 1977.
For their last gig of the year, The Libertines came back to their adopted hometown of Margate to finish off their latest tour.
Celebrating the birthday of David Bowie with his most legendary songs.