Accompanying a black and white portrait of her grandmother, the star wrote: "Our guardian angel. My beautiful, strong, creative, loving grandma. You are missed but your wisdom and love are with me and my family every day. I am so thankful for all of our wonderful times. I am so thankful for this beautiful heart."
Fans were quick to offer their support in the post's comments. One even wrote, "You have her smile."
The notoriously private actress is extremely close to her family, and grew up in Ohio before moving to Los Angeles to start her acting career. The star is the youngest of five siblings, and often takes Suri back to her hometown to see her relatives.
The 39-year-old star recently delighted followers on social media by posting a rare photo of her daughter.
"Can't believe how quickly she has grown up... Such a beautiful young lady," one fan observed in the comments section.
Katie has previously spoken out about the importance of giving her mini-me daughter as normal a childhood as possible, telling Town and Country magazine: "My child is the most important person to me, and her upbringing is paramount to my work right now… It's very important that I'm present and she has a stable, innocent childhood. I feel so blessed to do what I do, but there's nothing in the world better than watching your child succeed."