The 26-year-old played 45 minutes in a friendly against Croatia, scoring one goal to inspire Brazil to a 2-0 victory.
"It's been just three months since the injury. To be back and to do what I like most [in life], to play football, and to score a goal as well, is a great joy. I'm very happy. Yes, I'm not absolutely confident about my shape, but it's natural when you spend so much time without playing. I feel that I'm 80 percent ready," Neymar was quoted as saying by the French newspaper L'Equipe on Sunday.
Neymar has made 84 international appearances and scored 54 goals for Brazil since his senior debut in 2010, becoming the team's fourth highest-scoring striker, 23 goals behind record-holder Pele.
Brazil's final World Cup squad is to be announced later on Monday.
Russia will host its first-ever FIFA World Cup from June 14 to July 15 at 12 stadiums in 11 cities across the country. Five-time champions Brazil have been drawn in Group E along with Switzerland, Costa Rica and Serbia.