Neto signed a four-year contract with the Spanish champions.
The transfer was part of a swap which saw Barcelona sell Jasper Cillessen to Valencia.
Barcelona paid €26 million plus another €9m in variables for Neto, while Valencia paid Barcelona €35m for Cillessen.
Neto will replace Cillessen, who played as a backup for Marc-Andre ter Stegen in the Champions League and the Spanish league and only regularly started in the Copa del Rey.
The 29-year-old Neto helped Valencia qualify for the Champions League with a fourth-place finish in La Liga in the past two seasons.
