The shop – situated in the Upper Mall opposite M&S – closed at the end of April and temporarily moving to a pop-up store opposite Boots as work continued.
But now it has reopened with the top floor being extended and the whole shop refitted to create a "welcoming" space for shoppers at the busy centre.
H&M UK & Ireland Expansion manager Chris Clare said: "We’re excited to create a welcoming, modern and meaningful shopping experience in Merry Hill, where style, creativity and culture are celebrated.
"We’re super excited to share our new Merry Hill store with our West Midlands customers who will enjoy our amazing concepts and services. Our wide-ranging assortment and the introduction of HOME, Kids and Click and Collect means we are offering our customers more options than ever. We cannot wait to welcome our Merry Hill customers to the store today!”
Jonathan Poole, centre manager at Merry Hill, added: “It’s fantastic to see H&M re-open in a bigger and more sustainable store than ever after a significant investment in their presence at Merry Hill. The new and improved store houses a huge selection of men’s, women’s and children’s clothing, perfect for those looking to wrap up warm for the months ahead.
"The opening further expands the fashion offering available to our visitors, which includes Kurt Geiger, Mango, Dune London and the recently launched Ted Baker, it’s an exciting time at the centre. With more than 200 brands under one roof, thousands of car parking spaces and a month-long programme of festive events there’s never been a better time to plan a trip to Merry Hill.”