The two announced the partnership Wednesday, about seven months after signing a letter of intent to develop what they call a "strategic partnership."
Doug Cropper, Genesis President and CEO, says this will be "very positive for the community."
"This partnership brings more stability to Genesis Health System as part of a larger organization with more resources and national talent. And it helps us both to stabilize, grow, and develop more services for people within this region."
Bob Ritz is President and CEO of MercyOne.
"After today we will be providing care to about 38 per cent of all Iowans and after midnight today we will be touching about 4 million people in our systems and services locations."
Genesis provides health care in 17 counties of eastern Iowa and western Illinois, with a Quad Cities area workforce of more than 5,000.
MercyOne, with clinics, medical centers, and hospitals across Iowa, including Clinton and Dubuque, is a member of Trinity Health, a Michigan-based non-profit Catholic health care system. It has 88 hospitals in 26 states, with a total workforce of about 123,000.