So my daughter is 11 and she has this best friend from school. They have been close for almost two years now. At first I thought it was fine, just normal kids hanging out. But over the past few months I started noticing things. My daughter started talking back more, coming home later than she should, and last week I found out she skipped a homework session to go hang out with this girl at the mall without telling me. The thing is, this friend comes from a pretty different home situation. I am not judging the family, I really am not, but there is zero supervision over there. The mom works nights and the older brother basically does whatever he wants. My daughter used to be so responsible. Now she rolls her eyes at me when I bring up school. I want to handle this carefully because if I just ban the friendship, she will resent me and probably sneak around anyway. Has anyone dealt with something like this? What do you actually do?
Oh this hits close to home 
My son went through something almost identical when he was 12. His best friend at the time had basically no rules at home, staying up till 2am on weekdays, eating junk all day, parents never home. And slowly my son started thinking that was normal. The thing I did that actually worked was not cutting off the friendship but making our home the hub. I started inviting the friend over more so I could be around. Once you are in the mix you can steer things a bit without your kid feeling controlled. It takes patience but it is so worth it.
Honestly the eye roll phase is universal lol. Every parent thinks their kid turned overnight but a lot of it is just 11 year old energy. That said, I do think you have a right to set firm expectations regardless of who the friend is. The issue is not really the friend, it is your daughter making choices she knows you would not approve of. Address the behavior, not the person. If you go after the friendship directly, you become the villain and the friend becomes a rebel symbol. You do not want that.
I agree with GlassTech here. Going after the friendship head on almost never works at this age. What DOES work is having a really honest conversation with your daughter, not a lecture, an actual talk. Ask her what she likes about spending time with this friend. Listen without jumping in. You might learn something that surprises you. Kids at this age are figuring out who they are and sometimes they gravitate toward people who feel more free because they feel restricted at home. Not saying you are too strict, just saying it is worth thinking about.
Can I just say the mall thing would have sent me 
No warning, no text, just gone? That is a boundary issue full stop. I would have been at that mall myself looking like a whole scene lol. But in all seriousness, the solution I found with my kids is making the consequences really clear BEFORE things happen. Not after. Sit down when everything is calm, not in the middle of an argument, and go over what the rules are and what happens when they get broken. Make it feel like a team agreement rather than a parent decree. Kids buy into it way more when they feel like they had a say.
Something people do not talk about enough is getting to know the friend yourself. Like actually putting in the effort. I used to drive my kids and their friends to places just so I could be in the car and hear how they talked to each other 
You learn so much just by being present without being obvious about it. The friend might actually be a decent kid who just has a rough home setup. Or you might pick up on something that genuinely worries you. Either way you are making a decision based on real information instead of assumptions.
WovenLap said it perfectly with the hub idea. We did the same thing. Make your home the place kids want to be. Good snacks, a welcoming vibe, no interrogation at the door 
My wife always says if you want to know what your kid is up to, make sure their friends feel comfortable at your place. Works like a charm. Also building that kind of trust means your daughter is more likely to come to you when something actually serious happens, which at this age, it eventually does.
I will be the unpopular opinion here but sometimes a friendship just is not good for your kid and it is okay to say that out loud. You do not have to frame it as a permanent ban but you can absolutely limit how much time they spend together and under what conditions. Like, no unsupervised hangouts for now. Your daughter can still see her at school. She will be annoyed, yes. But you are the parent. The skipping homework and going to the mall without permission are not small things. That is a pattern starting to form and patterns are a lot easier to break early. Ask DroidPro about the mall situation 
some of us are not built for that kind of stress.
The thing nobody mentions is that you also have to keep working on your relationship with your daughter during this whole process. Because if she feels like you are always suspicious of her or waiting for her to mess up, she will just get better at hiding things. I went through two years of that with my oldest before I figured out that the more I pushed, the more distant she got. The shift happened when I just started spending more one on one time with her, no agenda, no talk about rules, just us doing something she liked. It sounds simple but it genuinely changed things between us.
Late to this thread but wanted to add something practical 
Write down the specific behaviors that concern you and talk about those directly with your daughter, not about the friend. Instead of saying your friend is a bad influence, try saying I noticed you have been coming home late and I want us to figure that out together. It keeps the door open. Also looping in her school counselor is not a bad idea if things keep going in the wrong direction. They see this stuff all the time and often have good suggestions that do not involve blowing up the friendship entirely.
Reading all these responses and I think the common theme is communication and presence. Both make a bigger difference than any restriction ever will. RigidDatum makes a fair point about limits but I think the way you do it matters more than the decision itself. If your daughter feels heard and respected she is way more likely to follow the boundaries you set. And honestly at 11 this is just the beginning. Better to build the right habits in how you handle these conversations now because the teenage years are going to throw you a lot more curveballs You sound like a thoughtful parent though, the fact that you are even asking this question says a lot.