Jennie, 30, and her restaurant manager partner Chris Farr are expecting their first baby together this year.
The Corrie actress shared the happy news on Twitter with the message:
"We have some news to share. Chris and I are expecting an addition to our family. Very happy x."
Jennie and Chris have been dating since 2005, and opened a restaurant together in 2012. Despite the long-term relationship, it seems marriage isn't on the cards any time soon.
Speaking last year, Jennie said: "I haven't got time. I don't like being the centre of attention so a big wedding isn't for me."
The couple's friends – and Jennie's co-stars – were quick to congratulate the pair on their announcement.
Michelle Keegan - who plays Tina McIntyre – said: "@jenniemcalpine arghhhhhhhhhhhhhh JEN!!!!!! SO SO excited for u!! Congratulations! Amazing news!!!!!! Xxx."
Dad Jack P. Shepherd – who plays David Platt – added: "Knew it! Well done! x."
Jennie's Corrie character Fiz has been on the cobbles since 2001, and is mum to daughter Hope. Hope arrived prematurely during the show's live 50th anniversary show in 2010.
In a recent interview with the Sun, Jennie said she has no plans to ever leave the street. ''I have spent my formative adult years on Coronation Street," she told the paper. "I've got some great mates at Corrie and they are like my family.