Does React.memo prevent Context consumers from re-rendering?

No. React.memo only performs a shallow comparison of a component's props — it has no visibility into context. If a component reads a value via useContext/Context.Consumer, that component re-renders whenever the context value changes, regardless of whether it's wrapped in React.memo and regardless of whether its own props changed.

const CountContext = React.createContext();

// Wrapping with React.memo does NOT help here
const Display = React.memo(function Display() {
const count = useContext(CountContext);
return <div>{count}</div>;
});

function App() {
const [count, setCount] = useState(0);
return (
  <CountContext.Provider value={count}>
    <button onClick={() => setCount((c) => c + 1)}>Increment</button>
    <Display />
  </CountContext.Provider>
);
}

Every time count changes, Display re-renders even though it takes no props and is memoized — React.memo bails out based on prop equality, but context consumption bypasses that check entirely.

How to actually reduce these re-renders

• Split contexts by concern so a component only subscribes to the slice of state it actually needs (see What's a common pitfall when using useContext with objects?).
• Memoize the provider's value with useMemo so the reference only changes when the underlying data changes — this reduces churn but doesn't stop consumers from re-rendering when the value itself legitimately changes.
• Push useContext down into a small wrapper component and pass the extracted value as a prop to a memoized child. The child (wrapped in React.memo) will now correctly skip re-rendering when that specific prop hasn't changed, since the memoization check happens one level below the context read.
• Use a state management library or selector-based API (Redux's useSelector, Zustand, Jotai) when you need fine-grained, per-field subscriptions instead of one large context object.