After playing for several amateur teams in the Birmingham area, Jenkyns joined Small Heath (later renamed Birmingham) in 1888. In 1889 the club first joined the Football Alliance and in 1892 became a founding member of the second division of the Football League. He had now made his debut for Wales and was club captain. In 1894 he made promotion to the first division as captain of Small Heath and defeated Darwen 3-1 in a friendly.

Known as one of the toughest defenders of his era, he was sent off four times at a game for Small Heath, at a time when such occurrences were extremely rare. His career in the Kleine Heide ended in March 1895 when