Sunderland manager Steve Bruce beat off competition from several other top flight teams for the 25-year-old who began his career at Charlton Athletic before moving to Brentford.
"Michael is one of the country's premier central defenders and I have had my eye on him for a while," Bruce told the Sunderland website.
Thank you for reading 5 articles this month* Join now for unlimited access
Enjoy your first month for just £1 / $1 / €1
*Read 5 free articles per month without a subscription
Join now for unlimited access
Try first month for just £1 / $1 / €1