Catherine was born in Seattle, Washington to Carey Giudici, who is of Swiss-Italian and Scottish descent and Cynthia Mejia, a Filipino American. Her maternal grandparents originated from the Philippine province of Pangasinan. She graduated from Roosevelt High School in 2004, and then from Washington State University in the class of 2008, having gained a B.A. in advertising. During this time, she dated Seattle rapper Grynch. She then began a career in advertising, working for Seattle's Wexley School for Girls.
The Lowes appeared on the first season finale of Bachelor in Paradise to speak to the final couples and assess the chances that their relationships would succeed.
Catherine was a guest on Jimmy Kimmel Live! with her fiance, Sean Lowe, just before their wedding. Kimmel told them that he thought they were lying about waiting until marriage, so he hooked them up to a polygraph test to find out the truth. The couple gladly agreed and the lie detector proved that they were truly waiting.
The Lowes were featured in Marriage Boot Camp: Reality Stars as they worked through their marital issues.
The Lowes also made an appearance on season 3 of Billion Dollar Buyer where they won a bid to sell products in their stationery line, LoweCo.
"This has been such a crazy journey and there have been so many unexpected, wonderful moments with you. I knew from the very beginning that you were someone that I wanted to be around, I just had no idea that my feelings were going to turn into what they've turned into. You never seize to amaze me, you never do. I think the world of you and I miss you every time we have to say goodbye, I miss you. I don't wanna say goodbye anymore. Catherine, I want to spend the rest of my life telling you "I love you", and making you feel like the most special, beautiful, woman in the world. Catherine... will you marry me?" - Sean proposing to Catherine.
"I am so grateful to have met somebody like you. I've never been so comfortable about myself and with somebody ever in my life and you're absolutely my best friend, and I can't wait, I can't wait. Forever" - Catherine to Sean.
Over a year after getting engaged, the two were married on January 26, 2014, in a live television ceremony performed at the Four Seasons Resort Biltmore in Santa Barbara.
On December 8, 2015, they announced via Instagram that they were expecting their first child. Their son, Samuel Thomas, was born on July 2, 2016.
On November 3, 2017, they announced that they are expecting their second child. Their second son, Isaiah Hendrix, was born on May 18, 2018.
On June 19, 2019, they announced that they are expecting their third child. Their daughter, Mia Mejia, was born on December 23, 2019.