In the throwback snapshot, which was posted on Instagram, the 43-year-old TV star resembled a glowing goddess with her golden tresses flowing in loose waves down her back.
The actress looked positively stunning in the picture as she flashed a warm smile and turned her head towards the camera. For the sunkissed selfie, Joanne opted for a minimalist beauty blend and chose to highlight her naturally pretty features with bold, feline eyeliner, dewy blush and a glossy pink lip.
Sharing the secret to her youthful appearance, Joanne captioned her post: "Looking back at some photos from the summer and at 43, I just can't believe how good my skin looks after my @ameela.uk treatment."
She went on to say: "I cannot recommend this skin booster enough for anti-ageing and hydration."
Awestruck fans and friends flooded the comments section with endless praise. Stunned by her glowing appearance, one follower wrote: "Gorgeous as always," while a second chimed in: "Wonderful photo and your skin does look amazing."
A third commented: "You absolute beauty! Love this pic [heart emoji] Hope you're doing well, Jo!" and a fourth sweetly added: "Absolutely gorgeous hope we see you back in Australia soon."
It's been an incredibly busy period for the actress! Back in October, the Golden Globe winner dazzled in silver at the launch of Manolo Blahnik: 'The Craft'.
Dressed up to the nines, Joanne looked picture-perfect in a glamorous metallic corset top which she teamed with a pair of high-waisted black trousers.
She elevated her glamorous get-up with a dazzling mirrored clutch and added some delicate pieces of jewellery for extra sparkle.
Joanne joined a plethora of guests at the private cocktail reception in Mayfair to celebrate the launch of the multisensory virtual and physical experience destination, xydrobe London.
Meanwhile, in September, the actress reunited with her Downton Abbey co-stars at Michelle Dockery and Jasper Waller-Bridge's fairytale London wedding.
For the special occasion, Joanne looked sophisticated in a breathtaking teal-hued maxi dress crafted by Ghost. Her chic gown was a real head-turner thanks to its billowing A-line skirt, capped sleeves and gleaming buttons.
The actress, who starred as Anna Bates in the hugely popular period drama, spruced up her look with a fitted white linen blazer from Topshop and a pair of towering white stilettos. Perfection!