For the special occasion, Joanne, 43, looked meticulously put together in a beautiful teal-hued maxi dress crafted by Ghost complete with a billowing A-line skirt, capped sleeves and myriad buttons running down the front.
The actress, who starred as Anna Bates in the hugely popular period drama, spruced up her look with a dazzling fitted white linen blazer from high-street favourite Topshop and a pair of coordinating white stilettos. Perfection!
She wore her flowing blonde locks in cascading waves and finished off her wedding guest attire with an alluring Manolo Blahnik clutch adorned with giant white polka-dots.
Joanne wasn't the only member of the Downton Abbey cast to support Michelle, 41, on her big day.
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Laura, who played Michelle's on-screen sister Edith Crawley, was one of several bridesmaids. The 37-year-old looked breathtaking in an elegant sea green gown featuring a chic boat neckline and a figure-skimming skirt. She looked picture-perfect as she exited the church clasping a bouquet of beautiful purple flowers.
Lily, meanwhile, turned heads in a striking Edem floral gown which she paired with a cream Galvan coat and a satin bag.
Back in August, the actress was spotted strolling hand-in-hand with her rumoured new partner, whose name is Mark, whilst enjoying a walk in the Buckinghamshire countryside.
Dressed down in black sportswear and a raincoat, Joanne appeared to be in relaxed spirits as she walked alongside her beau and their pet pooch.
While not much is known about Joanne's new romance, it seems this is her first relationship since her split from her ex-husband, James. The former couple confirmed their split back in February 2020, just before the COVID-19 lockdown took hold.
Despite her marriage breakdown, Joanne has previously spoken about how "grateful" she is for what she has.
Speaking to Red Magazine, she explained: "I didn't think I'd be divorced, I didn't think we'd be going through a pandemic, I didn't think my life would be in flux in the way it was. But I'm OK with that."
Since their split, Joanne has taken over the former couple's joint production company called Run After It. "I've taken that over now, so I'm running my own company," she revealed.
Reflecting on the importance of surrounding yourself with loved ones, Joanne went on to say: "I'm so grateful for my friends and family, for my health and to have been working so much during this past year. You realise, when it comes down to it, how many positives you have in your life."