Despite a lackluster season for Waterbury, Walker was offered a position with the defending champion Newark Little Giants, an International League team. Together, with pitcher George Stovey, Walker formed half of the first African-American battery in organized baseball. Billed as the “Spanish battery” by fans, Stovey recorded 35 wins in the season, while Walker posted career highs in games played, fielding percentage, and BA. Walker followed Newark's manager Charlie Hackett to the Syracuse Stars in 1888. Although he slumped at the plate during his two years playing for the Stars, he was popular among Syracuse fans, so much so that Walker was their unofficial spokesman and established business ties in the city. On August 23, 1889, Walker was released from the team; he was the last African-American to play in the International League until Jackie Robinson.