The seat has had the highest majority of any party in the past two elections, with Adams' current majority being 19,639.
Grigg, 39, works for New Zealand Trade and Enterprise in Canterbury helping mainly Canterbury-based agricultural exporters.
She was born in Canterbury and grew up on a sheep and beef farm in Mt Somers.
She studied at the New Zealand Broadcasting School in Christchurch working at some point for Newstalk ZB and RNZ.
In 2011 she was in a relationship with former All Black captain Richie McCaw.
In a statement about her selection today, she said the people of Selwyn knew the value of hard work and expected their Government to spend their tax dollars wisely.
"Labour and its coalition partners have talked a big game but failed to deliver on its promises."
She also paid her former boss a big compliment.
"Having worked for Simon Bridges, I've seen up close his intellect and understanding of what truly matters to Kiwis.
"He and his team around him know to run the economy to make sure it's thriving and able to meet the needs of all New Zealanders."