Switch the connected blockchain by clicking on the tab saying Main Ethereum Network, we need to add the Harmony One network.

Scroll down until you find Custom RPC.

Enter in the Harmony One mainnet settings as follows:

• Network name: Harmony Mainnet

• RPC URL: https://api.harmony.one

• Chain ID: 1666600000 (shared 0)

• Currency: ONE

• Explorer: https://explorer.harmony.one/

Click Save.

You have now connected to the Harmony One mainnet with your Metamask Wallet!