The instant multi-platform messaging service will provide passengers with an alternative to communicate directly with ScotRail.
Passengers can also communicate with the operator by visiting the website or messaging directly with the provided phone number.
The launch is part of £4m investment plan following a remedial agreement between ScotRail and Transport Scotland to enhance customer satisfaction.
ScotRail head of customer operations Phil Campbell said: “We are always looking for new and innovative ways to speak with customers, which is why we are so excited to launch WhatsApp.
“Our £4m remedial plan investment will help to deliver the service our customers expect and deserve.
“We know we still have much to do to regain the trust of our customers, but the unprecedented investment we are making is already paying off, delivering more seats, more services and faster journeys across the country.”
The remedial agreement also encompasses establishing two regional customer advisory groups, which will procure first-hand customer feedback.
ScotRail will invest in improved devices for frontline staff to enhance access to real-time disruption information and increase ‘deep clean’ frequency to improve cleanliness.
Additionally, it will distribute Delay Repay and refund information cards among the passengers affected with service disruption.
Overall, ScotRail is investing around £22m to improve reliability and punctuality of train services.
The ScotRail franchise is operated by Abellio, which is scheduled to run the service until 2025.