The young actress shocked her fans by leaving the show, where she was involved in a number of harrowing storylines as troubled teen Nicole Brodie.
But she hasn't let the grass grow and was immediately snapped up by the UK Screen Acting Academy, run by husband-and-wife team Stuart and Julie McGowan.
The Airdrie-born star said: "I was privileged enough to work on River City for a good number of years, but I wanted to get involved in other things, so I took the brave step of leaving the show.
"It felt simultaneously terrifying and exciting.
"I stumbled across the UK Screen Acting Academy and I felt it would be right up my street and that I would have a lot to offer.
"As well as being an actor, I have also taught drama and musical theatre over the years, so I was keen to get involved.
"I sent my acting and teaching CV to Stuart and had a meeting with him the same week - luckily we were on the same page.
"The academy is expanding all the time, so he offered me a job at their sessions at Strathclyde University and I accepted right away.
"The kids are absolutely brilliant - they are all young actors trying to learn and there's a very nice atmosphere."
Holly, who now lives in Glasgow, is delighted she has found a niche in the market, where the emphasis is purely on acting for the screen.
She added: "Most of the places kids can go to split up their classes between singing, acting and drama.
"But not every child can sing or wants to dance, so up until now, they have been left out. There's also a huge difference between screen acting and stage acting.
"I wish something like this had existed when I was younger.
"I grew up around musical theatre, which I still love, but I always wanted to do TV and film. Teaching is something I really enjoy, it's good to keep busy."
The 23-year-old is relishing the opportunity to help produce a new generation of young Scottish actors.
She said: "That's exactly what I want to do and I would find it very fulfilling.
"We want to reach kids who don't dance and sing. I know from experience that casting directors are looking for people who have studied screen acting and are raw and natural."
Company founders Stuart and Julie already have a high-profile success from within their own family, after their son Lewis starred in a previous John Lewis Christmas advert.
Julie said: "The UK Screen Acting Academy are excited to welcome Holly Jack to the team as one of our new acting coaches.
"All the actors are excited to work with Holly and feel that they can learn a lot from her experience on set in River City.
"At the academy, we don't sing we don't dance, we just act.
"The school will be teaching students specific acting techniques for film and TV, which is something lacking in Scotland and very rare in the UK."