Sunday started his career playing for local club Kumasi Asante Kotoko, of which he became the captain. In 1970, he and his club won the African Cup of Champions, predecessor of the CAF Champions League, the first international title obtained by the club.
A midfielder, he played the majority of his career for Ghanaian club Asante Kotoko, and was also a member of the Ghana national team, participating in two Africa Nations Cup tournaments. In 1971, he won the African Footballer of the Year award. In 1975, Sunday moved to Werder Bremen in the German Bundesliga, where in two seasons he barely had any playing time, appearing in only one league match against Rot-Weiß Essen in December 1976.
He was first named to the Ghana national team in 1966, and his first official international tournament was the 1968 African Cup of Nations, where he scored a goal against Laurent Pokou's Côte d'Ivoire on the semifinal won by Ghana 4-3. The Black Stars lost the final to DR Congo. At the 1970 Nations Cup, there was a rematch of the semifinal from two years before; Ghana defeated the Ivorians again 2-1, with Sunday scoring the opening goal.
However, they lost in the final again, that time to hosts Sudan. The 1970 final was Sunday's last Nations Cup match, as Ghana failed to qualify for the 1972, 1974, and 1976 continental tournaments. In 1971, while playing for Kotoko, Sunday was named African Footballer of the Year (Ballon d'Or) by French magazine France Football, being the first of three Ghanaian footballers that have earned such distinction to date. Ghana then qualified for the 1972 Olympic tournament in Munich, and Sunday was part of the Olympic squad.
As a coach, he has managed his former club Asante Kotoko, leading them to their second African Cup of Champions victory in 1983. He also managed Abuakwa Susubiribi and Ashanti Goldfieds of Ghana, FC 105 of Gabon and Côte d'Ivoire club Africa Sports of Abidjan, whom he also led to a the continental title in 1992..