Rob Lowe celebrates son John's 21st birthday in Vegas -- see the pics!

Rob Lowe is a total cool dad.

The 52-year-old actor helped his son, John, celebrate his 21st birthday in Vegas at OMNIA Nightclub inside Caesars Palace on Friday night, both looking handsome in black button down shirts and black pants. Patrick Schwarzenegger, 23, was also there for the festivities, looking sharp in a gray and white shirt. The group posed for a pic together, along with Rob's older son, Matthew.

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John definitely had a lavish birthday to remember, partying with the crowd who held up giant cut-outs of his face. Resident DJ Calvin Harris performed his hits, as the group was escorted to a VIP table.

John seemed excited to be celebrating his birthday in Sin City with his family and friends, a source tells ET, as the group sipped cocktails, danced, and took photos together. However, Rob didn't partake in the cocktails -- the actor has been sober for over 25 years.

Aside from his club night, Rob's youngest son also had a more low-key birthday celebration with just his family, including his mother, Sheryl.

"#Birthday #vegas 21 and done!!" Rob instagrammed a cute snap of the family of four enjoying a chocolate birthday cake.

Rob Lowe on Instagram
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Rob Lowe on Instagram
Getting ready! Mental Samurai is TONIGHT 9/8 central on @foxtv
Celebrating my #birthday with a #workout and @johnnylowe Whatever your age, be your best! #men #results @profile4men
Me and the boys getting at it last weekend. #karaoke #rock
Golf buddies.
Bonding. #dad #son #ocean
Merry #Christmas from our #family to yours! May your be blessed in the New Year.
Nothing is possible without #family #hollywoodwalkoffame #happy
At the #Duke game with the birthday boy! Go Matthew. Go Blue Devils. #football
A boy and his (brother's) dog. #Man #BestFriend
The Lowe boys take Hawaii! No fish is safe, no wave is too gnarly. It's on.
Nothing better than having the #boys back home for #summer. Can't believe I got them off the couch for a hike!
#birthday #vegas 21 and done!!
Repping for The Sheriff. #superbowl
Break in the action on set today. #WildBill
Cheers to an awesome holiday! Can't wait to head home to the newest addition to our family - Young Jack! Show me how you brought your dad-game this holiday season for your kids using #DadLife! @CocaCocaLife #Sponsored
New year, same ugly faces 😏 #happynewyears
The Lowe boys in the wilds of Hawaii. #adventure

Rob also proudly showed off his and John's matching good looks.

"#Father and #son #portrait 21st #Birthday #weekend #vegas," he Instagrammed another pic.

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#father and #son #portrait 21st #Birthday #weekend #vegas

A post shared by Rob Lowe (@robloweofficial) on

WATCH: Rob Lowe Hilariously Spoofs Matthew McConaughey's Lincoln Commercial

ET spoke to the forever youthful Rob in September on his first day on set of CBS' Code Black, which had him jumping out of a helicopter.

Watch below:

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