Reese Witherspoon Sheds ‘Tears of Joy’ at Niece’s High School Graduation: ‘Such a Proud Aunt’

Reese Witherspoon is one proud aunt.

On Monday, May 27, the actress, 48, shared her pride after her 18-year-old niece Abby graduated high school.

“Tears of joy for my incredible niece @abbyjameswitherspoon ! 🥹,” began her caption for a carousel of Instagram photos from Abby’s graduation day. “Congratulations on all the hard work, long hours of studying, the endless hours of test taking and essay writing ... and biggest congrats on being the joyful, kind- hearted, energetic, funny girl we are all so proud of ! 💓🎓 Such a proud aunt 😊.”

In the first snap, Witherspoon smiled as she posed alongside her niece and placed her arm around her shoulder. The Morning Show star dressed in a floral wrap dress for the celebrations, while Abby also wore white as she sported a crochet-style, floor-length dress.

The photo was followed by a solo shot of Abby holding a bouquet of fuchsia flowers and her graduation book, along with a snap Witherspoon had captured during the ceremony of Abby with her sister Draper.

Further photos in the carousel showed Abby posing alongside a giant number two and four in a backyard. The numbers had been decorated in green and white check.

The teen was also presented with a cake piped with a floral decoration and iced with the words, “Congrats AJ" for the special occasion.

The PEOPLE Puzzler crossword is here! How quickly can you solve it? Play now!

Abby and Draper are the daughters of Witherspoon’s older brother John, 51. Abby has followed in her aunt's acting footsteps on numerous occasions, having starred in Witherspoon's 2015 film Hot Pursuit, as well as 2022's Secret Headquarters, which starred Owen Wilson and Michael Peña. Later this year she will appear in Boys of Summer alongside Mel Gibson.

Witherspoon's graduation celebration comes after she shared her well-wishes with pal Jennifer Garner following her 18-year-old daughter Violet’s pre-graduation sendoff last week.

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer​​, from celebrity news to compelling human interest stories. 

After the actress, 52, posted a series of photos on Instagram of herself crying while attending her daughter’s Class of 2024 pre-graduation sendoff ceremony, Witherspoon wrote in the comments section, “Oh honey ... I know. 😢 ❤️ You have done a great job, mama! I will be here for support and lots of hugs.”

Witherspoon is mom to daughter Ava Phillippe, 24, and son Deacon Phillippe, 20, with her ex-husband Ryan Phillippe, as well as son Tennessee James Toth, 11, with her ex Jim Toth.