Bloxham, who has been with the Steel for the past 11 seasons as an assistant and head coach, signalled she was leaving to pursue and international opportunity.
She did not disclose where she is heading once she finishes with the Steel after their final ANZ Premiership game next Saturday.
"Stepping away from Steel wasn’t an easy decision for me to make," Bloxham said.
"I’ve played all my netball here in the south and this is where I became a high performance coach so moving away to take this opportunity was not done lightly," she said.
"Part of my decision to move is about change and doing something that makes me uncomfortable and rattles my bones a bit."
Bloxham has spent the past eight years at the helm, guiding the team to two ANZ Premiership titles in 2017 and 2018.
But her southern connections date back to her time as a player with the Southern Sting and brought her full circle as coach of the Steel.
"The experiences I had as a player have allowed me to understand what it takes to win and I have tried to take the winning mindset into my coaching," she said.
"My time at the Steel has shifted me from a person who enjoyed coaching netball at all levels because of my love for the game to someone who has made a career of coaching and moved into the performance coach zone
"My coaching journey has had its highs and lows but each experience has made me a better coach. It has made me look at why I do this. For me it’s about the people you meet along the way and making sure I stay true to who I am and my personal values."
Reaching the decision to leave had provided a chance to reflect on her career highlights, including back-to-back titles, their resilience after the 2017 van crash and the super club titles.
"I also enjoy watching the players improve and grow as women, on and off the court. Seeing them represent their countries and themselves so proudly is incredibly satisfying.
"And I have to rate the community we have and how they support this team as an absolute highlight. It’s humbling to have such a loyal extended whanau for the Steel."
It has been a challenging past two seasons for the Steel.
They suffered a 21 game losing streak and have only notched two wins this season, but it made Bloxham a better leader.
‘’The biggest learning for me has been around resilience and, as a leader, making sure that I turn up every week prepared and ready to win each and every session," she said.
"It has allowed me to focus on my coaching, really try to simplify things, break it down and move forward. Learning is key for me and there have been plenty of lessons, but trying to determine what learning you take each week and then deliver it with energy and clarity."
An international coaching gig always featured as part of Bloxham’s long term plan.
Bloxham helped Wales at the Netball World Cup last year, which fuelled her passion for the international level, but she did not disclose where she was heading once she leaves the Steel.
"It’s always hard to know when the right time for change is. From my perspective, the move is about me continuing to grow and learn and expand my coaching skills and knowledge.
"We have a great set up here in New Zealand for coaches who are supported well in our roles and have a tangible pathway which can lead to a variety of opportunities both here and overseas."
Steel chief executive Sonya Fleming said the head coach role would be advertised from Monday.
"Reinga has had a massive impact on our franchise, our sport and our players across all levels of the game here in Southland and her valuable input will be missed.
On the flip side, it is fantastic to see one of our own homegrown talents seeking new experiences on the global stage and we wish her all the best in her future endeavours," she said.
"For us, the hunt now begins for a high calibre and dynamic coach who can take the Steel in a new direction. I am excited to see who emerges from this recruitment process."
