Jenna and Tom, who are rumoured to have been dating for a year, play a young Queen Victoria and Prince Albert respectively.
In the second series Victoria will learn how to balance raising children with her duties as a wife and as a monarch.
Tom Hughes and Jenna Coleman will return for the second series of Victoria
Screenwriter Daisy Goodwin, who studied Victoria's diaries as a university student, said: "Even though she reigned in the 19th Century, Victoria is a heroine for our times. In the next series she faces the very modern dilemma of how to juggle children with her husband and her job.
"As Victoria will discover, it's hard to be a wife, a mother and ruler of the most powerful nation on earth!"
The couple, who are rumoured to be dating, with screenwriter Daisy Goodwin
Victoria launched at the end of August and has pulled in an average of 7.7 million viewers, making it the top rated ITV drama of the year so far.
Damien Timmer of producers Mammoth Screen said: "Following the audience response to Victoria we are delighted that the extraordinary Jenna Coleman will be returning to her throne for a second series.
"The next few years of Victoria's reign are packed full of extraordinary real life events, with constitutional crises, scandals at court and personal challenges aplenty for the Queen and Prince Albert. God Save the Queen!"
Jenna said it was "an absolute gift" to bring the monarch to life
At the show's press launch which HELLO! Online attended last month, Jenna, 30, opened up about playing the extraordinary monarch.
"The more I read the script, the more it unfolded in front of me and it was impossible to turn down," she said. "I would be crazy to turn it down, it's a gift, an absolute gift to try and bring this to life."