Mothercare has brought in Mitchell Kaye's agency for an undisclosed budget to 'build brand loyalty and relevance through a series of new moments and brand activation'.
The chain is undergoing a £35m overhaul that will involve the closure of about 100 stores and the loss of some 800 jobs. Its Early Learning Centre stores are expected to be hit hardest.
The firm is expected to take three years to return to profit.
The company commenced a brand relaunch this week by recruiting the services of singer-turned-presenter Myleene Klass to open a new 30,000 sq ft store, in Edmondton, north London.
The store features an indoor assault course to road-test prams and buggies.
Mischief will support the Mothercare press office and marketing team, reporting to newly appointed CEO Simon Calver. It won the brief following a competitive pitch and does not replace an agency.
Kaye said: 'Mothercare is an iconic brand with an incredible heritage. We're on board to help them write the next chapter of their story.'