He was named "Artillery Billy" after his stint as bombardier in the Royal Horse Artillery and also due to his awesome shooting power with both feet. Hartill was a sensational goalscorer for his first club, Wolves, scoring 170 goals in 234 games, grabbing 16 hat-tricks and was at the time Wolves' all-time leading scorer, but is now third in the list behind John Richards and Steve Bull. Hartill scored 30 out of Wolves' 115 goals on their way to the second division title in 1932. Promoted Wolves struggled in the First Division, finishing twentieth out of 22 teams, but Hartill scored two consecutive hat-tricks and four against Huddersfield. Wolves finished in the lower half of the table in the next two seasons with Hartill adding 46 goals to his Wolves tally, specializing in the "hook shot". In July 1935, the 30-year-old joined Everton to replace the great Dixie Dean, but he never settled there and joined Liverpool six months later. The Liverpool Echo commented on the Reds' capture of Hartill, who became the fourth former Blue on Liverpool's books along with Tosh Johnson, Jack Balmer and Alf Hanson: "He is a player admirably suited to the more open style of Liverpool. He is fast, can shoot with either foot, is good with his head, and takes up excellent position." Hartill was supposed to fill the gap of Gordon Hodgson who had left for Aston Villa the previous day. Hartill had already a big task on his hands to replace the legendary marksman and he failed to do so like he'd struggled to replace Dixie at Everton.

Hartill's brief Liverpool career was condensed into four games between 18 January and 22 February 1936. His introduction into the team coincided with a terrible goal drought in which only two goals were scored in seven matches, both by Jackie Balmer. Hartill disappeared almost as quickly as he had arrived. He became part of the deal that brought future legend Phil Taylor to the Reds from third division Bristol Rovers in March 1936. Hartill scored 19 goals in 36 games for Rovers before leaving the club in 1937, playing for amateur side Street until his retirement in 1940.