“This…” the Out of Sight star, 48, Instagrammed the image of Rodriguez, 42, cuddling up to his daughters – Natasha, 12, and Ella, 8 – and her 9-year-old twins Max and Emme.
The baseball star also shared some snapshots from the weekend birthday bash.
“Great weekend celebrating with our #families. #3generations,” he Instagrammed the group photo.
“Feeling so fortunate today for having these two lil angels in my life #thankyougod #itsmybirthday #familia,” he captioned another image.
Last month, the singer-actress posted photos of her boyfriend playing with her two kids.
Earlier in June, the On The Floor hitmaker shared a group shot in the pool.
In May, the Selena star and the retired baseball star attended the Met Gala together.
“It’s very simple. I was having lunch somewhere and I saw him. He passed by,” J.Lo recently explained of how they met. “Afterwards I went outside, but for some reason I felt like tapping him on the shoulder and said, ‘Hi.’ ”
She added: “He texted me, said, ‘Let’s go out to dinner,’ and I said, ‘Okay.’ We had a nice dinner.”
While A-Rod is a “great guy,” she shut down the idea that she slept over after the first date.
“No,” the Waiting For Tonight singer said. “Mama don’t sleep over on the first date.”
Lopez raises the twins with ex-husband Marc Anthony, while Rodriguez co-parents his daughters with ex-wife Cynthia Scurtis.
Great weekend celebrating with our #families. #3generations (?: Ana Carballosa/ @lacarba) A post shared by Alex Rodriguez (@arod) on