What Is Wrapped Bitcoin? How WBTC brings BTC to Ethereum and DeFi

Bitcoin is the largest pool of value in crypto, but on its own, it cannot touch Ethereum’s world of lending, borrowing, and yield. Wrapped Bitcoin is the bridge. This guide explains how WBTC works, the mint-and-burn model behind it, the alternatives, and the custodial risks that set it apart from holding real BTC.

Wrapped Bitcoin, known by its ticker WBTC, is an ERC-20 token that runs on the Ethereum blockchain and is backed 1:1 by real Bitcoin held in reserve, so that one WBTC is always meant to equal one Bitcoin. Its entire purpose is to solve a fundamental incompatibility in crypto: Bitcoin, the largest and most valuable cryptocurrency, lives on its own blockchain and cannot natively participate in the decentralized finance applications built on Ethereum, because those applications run on smart contracts that Bitcoin’s design does not support.

An enormous amount of crypto wealth sits in Bitcoin, while an enormous amount of programmable financial activity happens on Ethereum, and for years, there was no way to bring the two together. Wrapped Bitcoin is the bridge. By locking real Bitcoin with a custodian and issuing an equivalent Ethereum token against it, WBTC lets Bitcoin holders put their Bitcoin’s value to work inside Ethereum’s ecosystem, lending it, borrowing against it, trading it, supplying it to liquidity pools, and using it as collateral, all without selling their Bitcoin exposure. It was the first widely adopted way to do this, and it remains one of the most integrated.

The idea is simple, but the details are where the important nuances live, and they are worth understanding before using WBTC, because the convenience comes with trade-offs that holding plain Bitcoin does not have. A wrapped token introduces extra parties and extra trust assumptions, and the question of who holds the underlying Bitcoin, and whether you can always get it back, sits at the center of the whole arrangement.

This guide explains what WBTC is, why it is needed, exactly how the mint-and-burn mechanism works, who the custodians and merchants are, and why they matter, a concrete example of using WBTC in practice, how it compares to native Bitcoin and to newer alternatives like cbBTC and tBTC, and the specific risks that come with holding a wrapped asset rather than the real thing. The aim is to let you decide whether wrapped Bitcoin fits your needs or whether plain Bitcoin is the cleaner choice.

Why Bitcoin needs wrapping

To understand why WBTC exists, you have to understand a basic limitation of Bitcoin. Bitcoin was designed as a secure, decentralized system for holding and transferring value, and it does that job extremely well, but its scripting language is deliberately limited and is not built to run the complex, self-executing programs known as smart contracts.

Ethereum, by contrast, was built specifically to run smart contracts, and decentralized finance, the ecosystem of lending protocols, decentralized exchanges, and yield platforms, is constructed almost entirely on Ethereum and similar smart-contract blockchains.

The consequence is that Bitcoin, despite being the largest store of value in crypto, simply cannot plug into these applications directly. A Bitcoin holder who wanted to earn yield or use their holdings as collateral in DeFi had no native way to do so.

This is the gap wrapping fills. The core problem is one of interoperability, the ability to use an asset from one blockchain on another, and wrapping is one of the earliest and most widely used solutions to it. By representing Bitcoin as a token that conforms to Ethereum’s technical standards, specifically the ERC-20 standard that Ethereum applications are built to recognize, wrapped Bitcoin makes Bitcoin-linked value fully usable inside the Ethereum environment.

The ERC-20 standard is a set of rules that makes a token fully compatible and interchangeable across Ethereum’s smart contracts, so a wrapped Bitcoin token can be lent, borrowed, swapped, and used as collateral exactly like any other Ethereum token.

Wrapping, therefore, reduces the fragmentation between Bitcoin’s huge liquidity and Ethereum’s rich application layer, turning Bitcoin from an asset that sits outside DeFi into one that can be put to work within it. That is the entire reason wrapped Bitcoin was created, and why it found immediate demand. 

How the mint-and-burn model works

The mechanism that keeps wrapped Bitcoin backed 1:1 by real Bitcoin is called mint and burn, and it relies on a three-party system of custodians, merchants, and users.

The custodian is a regulated entity that holds the actual Bitcoin in secure reserve; for WBTC, this role has been played by the digital-asset custody firm BitGo. The merchant is an intermediary, such as an exchange or crypto business, that interacts with users, performs the necessary identity and compliance checks, and distributes the wrapped tokens. The user is the person who wants to convert between Bitcoin and wrapped Bitcoin. These three parties, coordinated by a set of smart contracts, keep the supply of WBTC matched to the Bitcoin held in reserve.

The process works in two directions. To create, or mint, wrapped Bitcoin, a user requests WBTC from a merchant, who carries out know-your-customer and anti-money-laundering checks to verify the user’s identity. The merchant then sends the corresponding Bitcoin to the custodian, who holds it in reserve and mints an equal amount of WBTC on Ethereum, which makes its way to the user.

To reverse the process, or burn the tokens, a user who wants their Bitcoin back submits a redemption request, the WBTC is destroyed in what is called a burn transaction, and the custodian releases the equivalent Bitcoin from reserve. Because every WBTC in existence is meant to correspond to a Bitcoin locked with the custodian, the token maintains its 1:1 peg, and its price tracks Bitcoin’s price closely.

Importantly, both the minting and the burning are recorded publicly on the Ethereum and Bitcoin blockchains, so anyone can verify the activity, and the system is periodically subjected to proof-of-reserve checks that confirm the Bitcoin backing actually exists. This transparency is meant to give holders confidence that the wrapped tokens are genuinely backed, though, as the risks section explains, it does not remove the reliance on the custodian.