Despite his main role as a creator of chances, Willie was not averse to scoring himself and in his second season at Pittodrie led the club in goal scoring with 28 League and Cup goals. The following season Mills was joined in attack by the aforementioned Matt Armstrong and the two went on to develop a seemingly telepathic understanding.

In 1935 the Scottish selectors recognised Willie's talents with an invitation to tour North America as a member of a representative side (during the tour he scored 14 goals in 11 games) and Willie also participated in the Jubilee International against England but in those days caps were not awarded for such games and Mills had to wait until October 5th 1935 before receiving his first full cap against Wales in Cardiff, the same game in which Matt Armstrong made his full Scottish debut. Willie was afforded two more chances to shine in the Dark Blue of Scotland again with Armstrong in November 1935 and finally "on his own" against Wales at Dens Park in 1936. Legendary Ranger Bob McPhail probably prevented Willie from becoming the established choice at inside-left, although Willie's talent surely deserved more recognition and in a different era would almost certainly have done so.

In March 1938, like so many Dons Internationalists before him, Willie was lured south by the better wages of top flight English football and Huddersfield headed the queue of clubs keen to gain Willie Mills' signature with a £6,500 bid. Willie enjoyed little over a season at Leeds Road before the war effectively ended his first class career but he continued to display his talents after the war at Highland League outfits Lossiemouth and Huntly. Died: Aberdeen, 25th May 1990