The pair played in the final pre-season friendly against Bristol City under-23s last weekend and will now be available for Saturday’s Vanarama National League opener at Barnet.
Defender Hutton, 20, arrives in Somerset having signed a new two-year deal at St Andrew’s in May having starred for the under-23s in their PDL 2 campaign.
Starting his career in the Midlands with Walsall, the attacking full-back made a name for himself at Hednesford Town to earn a second shot at professional football with the Blues.
In similar fashion to Hutton, winger McCoy joins the green and whites having penned a new one-year deal with his parent club this summer.
Also featuring for the development squad, the 21-year-old was instrumental in helping reach the PDL North runners-up spot and the final of the National Play-Offs during his 31 appearances in 2018/19.
Picked up by Birmingham from Beaconsfield in the Southern League, McCoy now arrives for a second taste of non-league football.
Adding his two latest recruits, manager Darren Sarll commented: “The pair have real quality and add substance to our currently small squad. A key element in their arrival is utilising my background in transforming young players into senior players.
“With that, I have to thank Birmingham City – and in particular Kristjaan Speakman, Stuart English and Chris Curtis – for entrusting me with their young people in the next stage of development.”