The pair, who broke up after Thompson reportedly cheated on her with Kardashian family friend Jordyn Woods, was seen celebrating their daughter's special day together.
Although they didn't post any photos together, they both shared photos and videos from the day, and Thompson could be seen on the edge of the frame during one video Kardashian shared to her Instagram Story of herself and True.
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"Whose birthday is it?" someone off-camera says.
"Baby True!" Thompson coos, puckering his lips for a kiss from his daughter. "You play with the jewels? I know, right? You deserve all the jewels, baby girl."
"My princess. I love you soo much," Thompson captioned the father-daughter footage from the party.
Kardashian shared a plethora of videos from the over-the-top event, showing off her and True's matching mommy-daughter dresses. "Mommy and me matching dresses by @augustgettyatelier," she captioned a video on her Story.
Kardashian's sisters Kourtney Kardashian and Kim Kardashian also shared videos from the party, where guests walked down a foggy path to a doorway decorated with paper umbrellas and an entry table covered with white balloons. Huge butterflies decorated a wall and a huge pastel rainbow balloon installation was the main attraction at the party.
Guests like Khloé's best friend Malika Haqq attended the party, as well as True's cousins North, 5, and Chicago, 15 months, who wore matching dresses embellished with orange feathers.
Kim, who shares North and Chicago and son Saint with husband Kanye West, shared a funny video showing North posing for photos in her mom's stiletto heels.
"OK, guys, peep North's shoes," Kim said in the clip. "She would not walk out of the house without my shoes."
Khloe marveled on her Instagram Story at how fast the past year has flown by.
"My baby is 1 today. Where does the time go?" the Keeping Up With the Kardashians star wrote on her Instagram Story on Friday, True's actual birthday. "Happy birthday my sweet True!! You are my ultimate True love! I am honored and so thankful to be your mommy! Today and until the end of time, I love you!! We have forever."
Khloé's mother, Kris Jenner, also took to social media to wish her granddaughter a happy birthday.
"Happy birthday to our beautiful angel True!! You are ONE today! [cake emoji] what a blessing you are to our family... You are the most precious gift, and I love you more than words can say #HappyBirthdayTrue #happygirl #sweetiepie," she wrote alongside a series of photos.0comments
Khloe and estranged boyfriend Thompson welcomed their sweet baby and first child together on April 12, 2018 in Cleveland, Ohio. She recently shared her disbelief that her daughter was about to turn one with PEOPLE in an interview.
"It's so corny but you don't realize how fast time goes by until you see a child growing in front of you. It's scary and sad because it goes so fast. Can we slow down time? I'm so utterly obsessed with her," she added. "This first year has been amazing. And I really feel like I was meant to do this."