Last month the record four-time winner of the African Footballer of the Year award told his Cameroon teammates he was quitting the national team.
His u-turn will be welcome news to the 'Indomitable Lions' who face Tunisia in Rades on October 13 followed by the return leg in Yaounde on November 17.
"You can have all the problems in the world but you have to see out your mission," the 32-year-old told Cameroon state radio.
"And this time it's to join my teammates in Tunisia and return with a good result."
He will link up with the national squad in the French Cote d'Azur resort of Nice on Wednesday to prepare for the match.
Eto'o made his debut for Cameroon, who are out to secure their seventh participation at a World Cup finals, in 1997.
He has regularly disagreed with Cameroon coaches and his initial retirement may have been linked to the selections of present incumbent Volker Finke.
The German reportedly ignored calls from Eto'o to start with goalkeeper Carlos Kameni and striker Achille Webo against the Libyans in their final group qualifying match -- Eto'o still played and from his corner they scored the only goal of the game to progress to the play-offs.
Shortly after that Eto'o announced he was retiring from international football.
Eto'o -- a member of the Cameroon side who won Olympic gold in 2000 -- was banned from the 'Indomitable Lions' last year after inciting a bonus-related boycott of a friendly in Algeria.
Recalled for a Cup of Nations qualifier against Cape Verde, he could not prevent Cameroon missing the 2013 finals in South Africa.
Born in Atlantic city Douala, he played for Real Madrid, Mallorca, Barcelona and Inter Milan before joining big-spending Anzhi, moving to Chelsea in the close season.