He was quickly spotted by nearby Woolwich Arsenal of the Football League, and signed as a professional for the Gunners in June 1900.
In 1901–02, Ashcroft kept 17 clean sheets in 34 League matches for Woolwich Arsenal, including six clean sheets in a row (a club record, that has only been equalled once since, by Alex Manninger in 1998); Arsenal finished fourth in the Second Division that season, and third the season after that.
He was sold to Blackburn Rovers in the summer of 1908 to alleviate the club's financial problems.
He played over 120 times for Rovers, and reached another FA Cup semi-final in 1910–11, and won the First Division title in 1911–12.
In 1913 he was released by Blackburn on a free transfer; unable to find a club, he had to place an advertisement in The Athletic News, which read: Ashcroft eventually signed for Tranmere Rovers, where he played for one more season before World War I intervened and all first-class football was halted; he seems to have retired from playing football at that point.