Work started earlier this month to replace the outdated cladding at the Debenhams entrance of the centre.
The work is being carried out by Solihull-based construction company mac-group, which has won its biggest retail contract yet.
Rockpanel cladding, which will appear purple/green or blue, is being installed, the entrance layouts are being reconfigured, and energy-saving LED feature lighting and large media screens are being installed.
Phase one also includes upgrading the façade at Argos & M&S using Rockpanel cladding in different gold shades and in a variety of finishes.
The final section of the works will be the upgrade of the areas around Primark and Sports Direct.
Projections such as diamonds and pyramids will be used to provide an impactful finish to the front elevation, the contractors said.
The modernisation programme is due to be completed in the third quarter of next year.
Ray O’Sullivan, director at mac-group, said: “Merry Hill is a prime retail destination for the region and we’re delighted to have been appointed for the first time by intu to transform the exterior of the shopping centre.
"It promises to be an extremely impressive finish, with discreet lighting hidden within the cladding, which will create a superb visual display, especially at night.”
Nick Round, regional centre director at intu Merry Hill, said: “We’ve seen a record-number of retailers invest in new or larger spaces at intu Merry Hill over the last 12 months, allowing us to offer an even better experience for local customers and those based further afield.
“The £12 million renovation is just one of the ways we’re planning to give back to our shoppers.
"Our long-term plan is to attract even more great brands to our mall and this redevelopment is just one of the ways we can achieve that.”