Cook bacon in a large, deep skillet over medium-high heat until crisp, about 10 minutes; drain on a paper-towel-lined plate until cool. Crumble bacon. Set aside.

Bring a large pot of lightly salted water to a boil. Cook elbow macaroni in boiling water, stirring occasionally, until tender yet firm to the bite, about 8 minutes; drain. Rinse macaroni with cold water until cool; drain again.

Combine macaroni, bacon, Cheddar cheese, mayonnaise, red onion, bell pepper, and ranch mix in a large bowl. Cover the bowl with plastic wrap; refrigerate before serving, at least 4 hours.