Located in Winter Road, the boutique is one of many stores getting involved.
From 10am the shop will be open and the celebrations will begin.
Portsmouth City Band will be in attendance to play festive tunes to the public while they shop, speak to staff and enjoy nibbles.
Alexsis Seed of Seeded said: ‘It’s really important for us as a small independent business to get involved each year.
‘It’s also a great opportunity for us to engage with our customers and the wider community to speak to them about what the Seeded creative community is about, over a mince pie and mulled apple juice.’