The agency will handle the creative work for the company’s East Coast and West Coast services.
Anomaly beat Grey London to the business in a final shootout, after a pitch that also included Lucky Generals and Y&R.
The train operator, which is 51% owned by Virgin Management, has worked with Krow Communications for three years. Krow declined to repitch when the account was put up for review last year.
It initially appointed Krow to its West Coast line before extending its remit to the East Coast line after Virgin Trains won the franchise in March last year.
Krow created the first ad for both services "Be bound for glory" in September last year.
Manning Gottlieb OMD handles Virgin Trains’ media planning and buying account, while TMW Unlimited oversees digital and CRM.
A Virgin Trains spokeswoman said: "We can confirm that we have undertaken a review for our creative ATL agency across both east and west coast but will not comment further while the process is still ongoing."
Anomaly could not be immediately reached for comment.