Grant (21) was named in the squad yesterday to take on Australia in two tests in New Zealand next month.
She was named in an initial wider training squad in March and spent three days this week at a Silver Ferns training camp in Auckland, before the 12-strong team was named yesterday.
"I didn't expect to make the team. I think my parents were just about as stoked as me, if not more," she said.
Grant said the camp in Auckland had gone well and had been demanding.
After final trial games on Thursday night, Aitken rang Grant to say she was in the team.
"I don't think it has sunk in just quite yet."
The Steel defender had a fine season for the southern side in the ANZ championship, after starting out slowly.
"We were a new side, coming together and it took a while to get going, but we all came together at the end."
She paid tribute to the Southern Steel and coach Robyn Broughton for getting her into the national side.
"I'd really like to thank the team [Southern Steel]. They have been great and Robyn has just been amazing."
Originally from Auckland, Grant came to Dunedin to play netball for the Rebels. She is in her third year in Dunedin, and is studying marketing at the University of Otago and human resources at the Otago Polytechnic.
She was not expecting to go straight into the starting seven, and said it was good to learn off the current players, and learn about the playing environment. The side named yesterday by Aitken included experienced defenders Sheryl Scanlan and Casey Williams, along with Joline Henry and Leana de Bruin.
Grant said the intensity of the ANZ championship had prepared her well for the training camp. The Silver Ferns play world champion Australia in Christchurch on September 17 and in Auckland three days later. The side also plays England in October, but a new squad will be picked for that series.
Grant's selection in the national team makes her unavailable to play for Otago in the upcoming national championships.
Aitken said Grant was was the big mover at the defence end during the ANZ Championship. She was very tenacious and never backed down.
"Especially against the Australian style, she will add real variety at the defence end."
Also named yesterday was Steel shooter Daneka Wipiiti, recalled to the team for the first time since 2002.
Features of the team announced yesterday were veteran Julie Seymour named as captain, with Magic players Laura Langman and Williams named as co-vice-captains.
Seymour (37), a mother of three, captained the team in 2002, and said the offer of the captaincy was more a pleasant surprise than a shock.
Seymour said she would treat the captaincy much like she did her career as a whole, in that she would review her commitment to the sport at the end of each year.
She takes over from Adine Wilson, who has stepped away from the court to raise her first child.
• The new Silver Ferns squad
Paula Griffin, Maria Tutaia, Irene van Dyk, Daneka Wipiiti, Maree Bowden, Joline Henry, Laura Langman (vice-captain), Julie Seymour (captain), Leana de Bruin, Katrina Grant, Sheryl Scanlan, Casey Williams (vice-captain).
