The 24-year-old French-born attacking midfielder has agreed an $8.7m (£5.1m) deal with a $67m (£40m) buy-out clause.
The Ivory Coast international, a free agent after leaving Galatasaray, left Stamford Bridge in 2012 after scoring the winning penalty in the Champions League final against Bayern Munich.
SATURDAY'S MATCHES
• Botswana vs Guinea-Bissau 2:0
• Uganda vs Mauritania 2:0
• Sierra Leone vs Seychelles 2:0
SUNDAY'S MATCHES
• Lesotho vs Kenya 1:0
• Tanzania vs Mozambique 2:2
• Congo Brazzaville vs Rwanda 2:0
• Benin vs Malawi 1:0
Gourcuff was last coach of Lorient, leaving the job in May at the end of the Ligue 1 season. He has also coached at Le Mans and Stade Rennes and had a one-year spell in Saudi Arabia.
2nd round - fixtures & results
SATURDAY (19th July 2014)
• Botswana vs Guinea-Bissau 2:0
• Uganda vs Mauritania 2:0
• Sierra Leone vs Seychelles 2:0
The Super Eagles climbed three places in the Confederation of African Football region and 10 spots on the global list - up to 34th in the world.
The 27-year-old centre-back was part of the Desert Foxes squad that reached the last 16 of the World Cup in Brazil - their best performance at a finals.
The Baggies announced the arrival of the 25-year-old Dynamo Kiev player on Friday, saying they had broken the club's record.
SATURDAY
• Botswana vs Guinea-Bissau
• Uganda vs Mauritania
• Sierra Leone vs Seychelles
SUNDAY
• Lesotho vs Kenya
• Tanzania vs Mozambique
• Congo Brazzaville vs Rwanda
• Benin vs Malawi
Ba joined the Blues from Premier League rivals Newcastle in January 2013 on a three-and-a-half year deal for an undisclosed fee.
GROUP F
Argentina vs Iran 1:0
Lionel Messi scored the only goal in the 91st-minute to send Argentina through to the World Cup knockout stage.
ANALYSIS
"Lionel Messi is the difference in so many games and he's done it again. You know what he's going to do, take a step and curl it, but there's nothing the magnificent Iranians can do. It is just world class."
Argentina
Iran