Pixie, who was watched by her dad Bob and sister Peaches, modelled a black and gold strapless bubble dress, ankle boots and a frilly black layered jumper, the Evening Standard reports.
Bartlett said: "The collection is a bit more down. No, not in that way, we don't mention the recession here.
"I mean that the colours are more down; more muted than in my current collection. There are more greys and blacks - they just feel more right for now."
Earlier this month, Pixie posed for the new Agent Provocateur catalogue, with one shot featuring her holding a hunting horn and wearing suspenders, knickers and a riding jacket.