How to bridge NFTs from Ethereum to Polygon? (Layer 2 guide)

Understanding the Bridge Mechanism

1. Ethereum and Polygon operate as separate execution environments with distinct consensus rules and gas economics. Bridging NFTs requires moving ownership representation—not the underlying asset—across chains using a trusted or trust-minimized protocol.

2. The Polygon PoS Bridge is the official, permissioned bridge maintained by Polygon Labs. It relies on a set of validators who collectively sign checkpoints on Ethereum and commit them to Polygon’s checkpoint contract.

3. When an NFT is locked on Ethereum, a corresponding wrapped version is minted on Polygon. This process is reversible: burning the Polygon token triggers unlocking of the original on Ethereum.

4. Only ERC-721 and ERC-1155 tokens are supported. Non-standard or custom NFT contracts may fail validation or require manual integration approval from the bridge team.

5. Transaction finality differs: Ethereum confirmations take ~15 minutes for safety, while Polygon finality is near-instant but depends on checkpoint submission intervals—typically every 30 minutes.

Prerequisites Before Initiating Transfer

1. A Web3 wallet such as MetaMask must be configured with both Ethereum Mainnet and Polygon network settings. Custom RPC endpoints for Polygon must be added manually if not auto-detected.

2. Sufficient ETH balance on Ethereum is required to cover the lock transaction fee. Gas prices fluctuate; users should monitor real-time estimates via Etherscan or GasNow before submitting.

3. At least 0.01 MATIC must be held on Polygon to pay for minting and future interactions. This can be acquired via centralized exchanges or the Polygon faucet for testnet use only.

4. The NFT contract address must be verified on both Etherscan and Polygonscan. Unverified contracts often trigger warnings or outright rejection by the bridge UI.

5. Ownership of the NFT must reside in the wallet initiating the bridge. Wrapped or delegated tokens held in smart contract wallets like Safe or Argent may encounter signature mismatches unless configured for EIP-1271 support.

Step-by-Step Bridging Process

1. Navigate to https://wallet.polygon.technology/bridge and connect the same wallet used to hold the NFT on Ethereum.

2. Select “Ethereum” as the source network and “Polygon” as the destination. Paste the exact NFT contract address and token ID into the designated fields.

3. Click “Deposit” to initiate the lock transaction on Ethereum. Confirm the wallet prompt. This step consumes ETH and emits a Deposit event visible on Etherscan.

4. Wait for the next checkpoint to be submitted and verified on Polygon. This usually takes between 22 and 45 minutes. Users can track progress via the “Checkpoints” tab on the bridge dashboard.

5. Once confirmed, the NFT appears under the “My NFTs” section on the Polygon side. It can then be viewed in OpenSea Polygon marketplace or transferred using standard ERC-721 functions.

Risks and Known Limitations

1. The bridge does not support batch transfers. Each NFT requires a separate deposit and withdrawal transaction—even for collections with identical contract logic.

2. Metadata URIs pointing to decentralized storage (e.g., IPFS) remain unchanged, but if hosted on centralized servers with CORS or referrer restrictions, display issues may arise on Polygon-native dApps.

3. Some marketplaces like Blur or X2Y2 do not index Polygon NFTs automatically. Manual contract addition or third-party indexer services like Covalent may be necessary for visibility.

4. If the Ethereum transaction reverts due to insufficient gas or nonce mismatch, no funds are lost—but the bridge UI may temporarily show a pending state until timeout occurs.

5. Withdrawals from Polygon back to Ethereum require a separate “Withdraw” action and are subject to a 7-day challenge period during which validators can dispute invalid burns.

Frequently Asked Questions

Q: Can I bridge an NFT that was minted on Polygon originally?A: No. The official bridge only supports one-way bridging from Ethereum to Polygon for deposits. Reverse bridging is only possible for assets originally deposited from Ethereum.

Q: Why does my NFT show as “unverified” on OpenSea Polygon after bridging?A: OpenSea relies on on-chain contract verification status. Even if the contract is verified on Polygonscan, OpenSea may lag in syncing metadata or require manual verification submission through their developer portal.

Q: Does bridging change the token ID or contract address on Polygon?A: The token ID remains identical. The contract address on Polygon is a deterministic clone derived from the original Ethereum address and bridge parameters—not a copy-paste of the same bytecode.

Q: Are royalties enforced across both chains after bridging?A: Royalty enforcement depends entirely on the marketplace implementation. The bridge itself does not alter or enforce royalty logic. Platforms like Rarible or Manifold must independently configure and honor royalty standards like EIP-2981 on each chain.