Born in Manchester, the defender joined the Manchester City youth academy at the age of 5. Whilst at City, he was loaned out to NAC Breda, Heart of Midlothian and Oxford United - whilst also featuring for the England youth setup.
The 5ft 10in wing-back joined Plymouth Argyle at the start of the 2018/19 season for an undisclosed fee, which 'Pilgrims boss Derek Adams later stated to be £10.
Ashley Smith-Brown made 26 appearances for Argyle last year in a season which ended in relegation for the Cornish side.
Will he feature for the Latics?
There may be some doubt surrounding whether or not Smith-Brown will get much game time this season for Oldham Athletic. The Latics already have a strong contingent of wing-backs, with Tom Hamer and Alex Iacovetti featuring on either side regularly last year.
Oldham have also signed proven League Two defender, Zak Mills, who has appeared to play as a right-back in the pre-season matches that have so far occurred.
What difference will he make?
Last season at Plymouth, Smith-Brown looked promising going forward, even if less solid defensively. With the Latics having such a strong contingent of defensive players, it seems as if having Smith-Brown play as a more attacking player will be something that Laurent Banide may look to do.
Against Forest Green Rovers, Mills played in a more attacking role, playing on the right-side of midfield. Oldham looked strong defensively in the first half, only letting Mark Cooper's side breakthrough a handful of times.
However, in the second half of the match, Tom Hamer and Alex Iacovetti did not seem as confident in the backline, and having Zak Mills further behind could make a difference.
Banide may choose to push Mills further back and into the defensive backline, with Smith-Brown now taking his more advanced role in midfield.
Of course, doing this would mean that either Hamer or Iacovetti would be forced out of the starting eleven, but with both being able to play on either side of the defence, this may not cause an issue.
What's in it for Argyle?
Smith-Brown was a regular starter for Argyle last season in a higher division, albeit in a season that they got relegated. In their recent match against Crewe Alexandra, Ryan Lowe's side adopted a back three.
The Manager also preferred to do that during his tenure last season which achieved promotion with Bury
Scott Wootton has been the player to start on the right-hand side of the defence and it seems as if Lowe prefers to have more solid defensive players in his backline.
Another season of professional football could drastically improve Smith-Brown as a player. Looking to the future, that may be something that Lowe would want if his side were to be promoted to League One, as they are aiming to.