Júlio César was the starting keeper of Brazil under-17 squad in the 1995 FIFA U-17 World Championship in Ecuador. He kept clean-sheets in all three Group Cmatches, respectively against Germany, Oman and Canada, helping Brazil finish on top. Brazil eventually made their way to the final, also defeating their rivals Argentina in the semi-final, only to lose 3–2 to Ghana.
Four years later, Júlio César was part of Brazil under-20 side in their 1999 FIFA World Youth Championship campaign. He was the second choice behind Fábio, making no appearances as Brazil was eliminated in the quarter-finals by Uruguay. Júlio César was first included in Brazil senior team for the 2003 FIFA Confederations Cup, where he did not play as the team was eliminated in the group stage. The next year, he was included in the squad for the 2004 Copa América, where he also made his first international appearance, starting in the opening Group C against Chile, keeping a clean-sheet as Seleção won 1–0. He become the 963rd player to play at least a match for Brazil. One of the best goalkeepers in the world in his prime, Júlio César was known for his athleticism, strength, and reflexes, as well as his agility, positional sense, shot-stopping, ability to read the game, and speed when rushing off his line. A left-footed goalkeeper, he is also known for his ball skills and distribution, as well as his penalty stopping. Júlio César is a Roman Catholic. He married Brazilian model and actress Susana Werner at the Candelária Church. Together, they have two children: Cauet, born in 2002, and Giulia, born in 2005. They both went to ACS Hillingdon International School. He is sponsored by Asics.