The couple tied the knot at the historic Langham Huntington Hotel in front of about 650 guests, including the publishing heiress' good friend Michelle Trachtenberg.
The bride, 31, wore a custom-designed pink Christian Siriano gown (which she previewed on Instagram a week before the wedding) and customized Stuart Weitzman shoes for the ceremony, where the guests wore cowboy boots and cocktail attire. The groom donned a custom Prada suit.
Guests enjoyed a four-course meal that included Chilean sea bass, beef filets and a delicious wedding cake.
A day before the wedding, Hearst shared a picture on Instagram with her comedian groom, 44, that showed her and the Talking Dead host as zombies. She captioned the pic, "My love for you will never die."
Nerdist CEO Hardwick proposed to Hearst in September 2015, with a huge diamond ring that belonged to her grandmother Catherine Hearst. Lydia's mom, Patty Hearst, "graciously and wonderfully passed it down to me to give to Lydia," he captioned an Instagram pic of the couple in a passionate lip lock after he popped the question.
Lydia, whose great-grandfather is the late publishing titan William Randolph Hearst, shared the same photo on Instagram, writing, "Every love story is beautiful, but ours is my favorite. You completely swept me off my feet. You have shown me what it feels like to be loved and I love you with all my heart. My life is better because you are in it."
The night before their nuptials the couple celebrated at a rehearsal dinner and Hardwick posted a sweet pic taken by Patty that showed him kissing his future wife. He hashtagged the Instagram photo #AllTheEmoji.
Lydia celebrated her bachelorette weekend at the end of July at her great-grandfather's legendary Hearst Castle in San Simeon, California, partying in style and even taking to the estate's decadently decorated indoor pool in colorful inflatables.
The newlyweds are set to honeymoon in Japan.