Spade was found dead in her New York apartment on 5 June 2018 aged 55. Her husband, Andy Spade, later revealed in a statement that the American designer had suffered from anxiety and depression for “many years”.
Brosnahan marked the anniversary by sharing an old photograph of Spade on Instagram, writing “Missing Katy B today” referencing Spade’s maiden name, which was the same as the actor's before the designer married.
The post has garnered more than 16,300 likes and thousands of supportive comments from Brosnahan’s 465,000 followers.
“Her brilliance will always be missed,” wrote one person. “Thinking of you and your entire family today.”
Another added: “I love what she is wearing here. She was an original. Happy she is out of pain.”
A post shared by Rachel Brosnahan (@rachelbrosnahan) on Jun 5, 2019 at 11:11am PDT
Spade was famed for her colourful and uplifting designs, with her playful handbags earning her a cult following of loyal fashion fans.
A post shared by David Spade (@davidspade) on Jun 5, 2019 at 8:23am PDT
Spade's brother, actor David Spade, also paid tribute to the fashion designer on Instagram by uploading a photograph of the duo together alongside a heart-shaped emoji.
In January, Brosnahan honoured Spade by fronting a fashion campaign for Frances Valentine, an accessories label the designer launched with her husband in 2016.
In the campaign, the actor posed wearing a selection of vintage-inspired ensembles paired with whimsical bags and shoes in a colourful, flower-filled showroom overlooking Bryant Park in New York City that is covered with the family’s own artwork.