The magnets are in the phone, not the case
The thing most people get backwards is where the magnets live. MagSafe is a ring of magnets built into the iPhone itself, not something a case adds. Apple builds it into the iPhone lines from the 12 up to the current 17, which is why a MagSafe charger locates itself on the back of a bare phone and holds there without any help. Apple's own way of describing it is that "the perfectly aligned magnets keep it attached to your iPhone", and the accessory is the half doing the reaching, not the phone.
You can see the same thing in Apple's setup instructions. To charge, you connect the charger to a 30W or greater USB-C adapter and then, in Apple's words, "place your iPhone on your MagSafe Charger". There is no step that involves a case, because the case was never part of how the magnets find each other. A case can sit in the gap or it can be absent; the charge works either way, as long as nothing is blocking the magnets from lining up.
So the honest one-word answer is no. A case is a protection and grip choice, not a charging requirement.
Which iPhones actually have it
MagSafe is an iPhone feature with a clear cut-off, so this is worth checking before you buy a charger for someone. Apple lists MagSafe support running from the iPhone 12 line all the way through the current 17 line, including the iPhone 17e and the iPhone Air. If the phone is in that range, the magnets are there and a MagSafe charger snaps on.
Below that line the picture changes. Apple groups the iPhone 16e, the iPhone 11 models, the iPhone X, XS and XR, and the iPhone 8 models as "non-MagSafe, Qi-compatible" devices, and warns that "power and charge times are different" when you rest a MagSafe charger on one of them. It will still charge, because the pad falls back to ordinary Qi, but it won't click into place and it won't behave like it does on a newer phone. That is a phone limit, not a case you can add to fix it.
When a case helps, and when it gets in the way
A case only enters the story once you have decided you want one for protection. Here is how the common kinds behave.
A thin, plain case usually charges through without complaint, because the magnets are strong enough to reach across a thin layer of plastic. A case sold as "MagSafe" goes further: it has its own matching magnet ring moulded in, so accessories land in exactly the right spot and the hold feels as firm as it does on a bare phone. That is the real thing a MagSafe case buys you, alignment and grip, rather than the ability to charge at all.
The cases that cause trouble are the thick ones and the wallet ones. A very thick or heavily armoured case can push the charger far enough from the magnets that the pull weakens or an accessory sags off. And a wallet or card-holding case brings a genuine risk, not just a weak connection. Apple's guidance is blunt: "don't place credit cards, security badges, passports or key fobs between your iPhone and MagSafe Charger", because that may damage the magnetic strips or RFID chips in them. If your case carries any of those, take them out before you charge.
Android and older phones: it is Qi2, not MagSafe
If the phone isn't a supported iPhone, MagSafe as a branded fit isn't the thing to shop for. The magnetic-snap idea has since been standardised by the Wireless Power Consortium as Qi2, and that is what other phones use to get the same click-into-place behaviour. Very few Android handsets carry the magnet ring built in, so on most of them a magnetic charger either grips through a dedicated case or simply rests flat and charges at plain Qi speeds. If you are buying for a non-iPhone, our Qi2 versus MagSafe explainer sorts out which label to look for and why a Qi2 pad is the safer buy than an Apple-branded one.
What to buy once you know a case is optional
With the case question settled, the buying decision moves to the charger and the wall plug behind it, which is where your real charging speed is decided anyway. If you want a magnetic pack you can walk around with, our MagSafe power bank guide picks ones that hold on a bare phone. For a base that charges an iPhone, an Apple Watch and AirPods together, the 3-in-1 wireless charger guide covers those, and for the car the MagSafe car charger guide does the same for a vent or dash mount. None of them need you to own a special case first; a supported iPhone is all the kit that is assumed.
FAQ
Q: Does MagSafe work through a normal case? A: A thin plain case usually charges through fine, because the magnets reach across it. A case sold as MagSafe adds its own magnet ring so accessories align and grip as firmly as on a bare phone. A very thick or heavily armoured case can weaken the pull, and a metal plate stuck on the back can block it.
Q: Is it safe to charge with a wallet or card case on? A: Charge it without the cards in. It is the cards that are at risk, not the phone or the charger: Apple warns the magnets can damage a card's magnetic strip or an RFID chip, so slide bank cards, passports and key fobs out before the phone goes down. The empty case itself is fine.
Q: Will MagSafe work on an Android phone or an older iPhone? A: Not as a snap-on fit. Apple treats older iPhones like the 11, X and XS as non-MagSafe Qi devices, where the power and charge times are different, and most Android phones have no magnet ring at all. Both still charge on the pad at ordinary Qi speeds; they just don't click into place.