You can import ether from Mist and MyEtherWallet into your Blockchain wallet. However, please note that we do not support ERC20 tokens at this time, though we may in the future. If you're currently using ERC20 tokens or have any smart contracts associated with Mist or MyEtherWallet, do not import your funds.
To import ether into your Blockchain wallet from Mist and MyEtherWallet, simply create a backup through your existing Mist or MyEtherWallet and download the resulting Keystore File. In your Blockchain wallet, navigate to your Settings on the left hand side of your screen and select General. You will see a new option to import funds from Mist and MyEtherWallet.
Once you’ve uploaded your Keystore File, enter your Mist or MyEtherWallet passphrase, click ‘Import Funds,’ and your ether will be transferred into your Blockchain wallet. Please note that an Ethereum network transaction fee will be charged to initiate the import.
Any funds received to Mist or MyEtherWallet after the import will not be imported to your Blockchain wallet or able to be recovered by your backup phrase. If you receive funds later, you can always go through the import process again.