They join Northern Mystics defender Carys Stythe to complete the defence end for next season.
Thomas, 23, has been a training partner with the New South Wales Swifts for the past three years and was eager to step into the ANZ Premiership next season.
“I am still in shock to be honest,’’ Thomas said.
"To have a club across the ditch believe in my capabilities and jump at the opportunity to have me in their squad is a dream come true. I am grateful beyond words.
“The past three years with the Swifts has enabled me to grow as a player in a very intense but professional environment. All I have ever wanted is to be a professional athlete and I wanted to branch out and have new experiences of my own in New Zealand."
Thomas has links to New Zealand through her Māori father, who was born and raised in Whangarei. She said she was not fazed about learning a new Kiwi defensive style and looked forward to learning under new coach Wendy Frew.
She played against the Steel when the Swifts played a pre-season tournament in Invercargill last year with former Steel coach Natalie Avellino in charge.
"It was such a fun experience and to be versing Silver Ferns made it very memorable", she said.
“Nat was our team mum in Invercargill, showing us the local town, attractions and people always stopping her for a chat. She showed us how friendly the town is. I haven't heard much of Nat's past with Steel, but I know when we were over there she felt very connected and had a sense of home. Natty is very pleased I have the opportunity and excited for me to embrace what Invercargill has to offer."
Lawson, who was a standout in her Steel return this season, looked forward to joining the Steel’s exciting mix next season.
“I’m really looking forward to being back in blue and pink with the Steel next year, with a new group of players and a new coach,’’ Lawson said.
"We have a very exciting team with a little bit of everything in the mix and I can’t wait to see what we can achieve together", she said.
They join midcourters Kate Heffernan, Kimiora Poi, Renee Savai’inaea and Serina Daunakamakama and shooters Georgia Heffernan, Aliyah Dunn and Summer Temu.
— The Mystics have filled the gaping hole left in their roster by the departure of Silver Ferns star Grace Nweke with Australian Diamonds shooter Donnell Wallam.
Nweke's decision to play across the Tasman next year meant the ANZ Premiership champions had to try to find a shooter with equal stature.
At 1.93m, Wallam is the same height as Nweke and is a strong holding shooter but also very mobile and one of the few tall goal shoots comfortable shooting from long range.
The Mystics have retained the majority of the current squad with eight players re-signing for 2025.
The only other change is the return of veteran defender Holly Fowler from the Stars.
The Mystics were on the hunt for another defender after Carys Stythe was signed by the Steel.
— Additional reporting RNZ
