Cook bacon in a large, deep skillet over medium-high heat until crisp, about 10 minutes; drain on a plate lined with paper towels until cool. Crumble the bacon.
Bring a large pot of lightly salted water to a boil. Cook elbow macaroni in the boiling water, stirring occasionally, until cooked through but firm to the bite, 8 minutes; drain.
Rinse macaroni with cold water until cool; drain.
Mix cooled macaroni, crumbled bacon, mayonnaise, red onion, green bell pepper, ranch salad dressing mix, and Cheddar cheese together in a large bowl.
Cover the bowl with plastic wrap and refrigerate at least 4 hours before serving.
