Paris Hilton's life "feels so complete" now she's a mother.

The 42-year-old star and her husband Carter Reum became parents to son Phoenix via a surrogate in January, and she's shared a touching message for her "angel baby" after he turned six months old over the weekend.

Alongside a series of photos of Paris wearing a pink heart-print tracksuit with her son on her lap, she wrote on Instagram: “This Barbie is a Mom.

“My baby boy Phoenix is 6 months old today.He is my world and makes my life feel so complete. Can't wait for all the magical memories we will create together! Mommy loves you so much angel baby.(sic)"

In May, Paris admitted motherhood had been an "incredible experience" so far.

Marking Mother's Day in the US, she wrote on Instagram: "So excited to be celebrating my first Mothers Day with my little angel baby Phoenix. Being a mom is the most incredible experience I have ever had. It's a love that cannot be put into words, a feeling that I never knew existed until I held my little prince in my arms. Watching him grow and learn every single day brings me so much happiness and fills my heart with so much love. [tears and hearts emojis] (sic)"

The blonde beauty also paid tribute to her own mom in the heartfelt message.

Paris' Instagram post continued: "There is something so special about being a mom, something that I never fully understood until I became one myself.

"This Mother's Day, I can't help but feel grateful for this beautiful journey I am on. It's a day to celebrate the incredible women who brought us into this world, who have loved us unconditionally and who have shaped us into the people we are today. My mom is my biggest inspiration and the original queen of my heart. She has always been there for me, through the ups and downs, and has taught me the true meaning of strength and love.

"To all the moms out there, I want to wish you the happiest Mother's Day. You are the backbone of your families, the glue that holds everything together, and the most important person in your child's life."