Reese Witherspoon and Ryan Phillippe reunited to celebrate their son's birthday together.

Reese Witherspoon

Reese Witherspoon

The Oscar-winning actress and her ex-husband were both present at their son Deacon‘s 17th birthday party, where they were joined by other family members for the celebration.

Reese, 44 - who was married to Ryan between 1999 and 2008 - is seen in an Instagram Story video bringing out a cake to Deacon while everyone sings 'Happy Birthday'.

Ryan, 46 - who also has Ava, 21, with the Hollywood star - is behind the camera filming the video clip.

The actress previously took to social media to wish her son a happy birthday, praising Deacon for being "hardworking, fun-loving and deeply kind".

She wrote on Instagram: "Happy Birthday to my wonderful son @deaconphillippe! ... My bright light/ hardworking / fun-loving / music making / deeply kind son, who always finds the good in everyone and everything. What a pleasure to watch you grow into an amazing young man who is always curious and endlessly creative. Can’t wait to celebrate! I love you so much ...#17 (sic)"

Prior to that, the 'Big Little Lies' star credited her children with "inspiring" her to speak out on social issues.

Reese - who also has Tennessee, eight, with her spouse Jim Toth - explained: “I have a lot of inspiration from having two teenagers in my house.

"Somewhere I read, ‘If you’re not talking about race and class and wealth and equality and social issue with your children they are talking about it with someone else.’ That hit me very profoundly because this is the world they are inheriting."