The sale included trucks and depots and about 130 staff based in Invercargill, Dunedin, Queenstown, Alexandra, Timaru, Christchurch and Nelson.
Tulloch Transport managing director Ian Tulloch said more than 100 of those staff had kept their jobs, but there were some redundancies where the two transport operators had duplication.
TNL did not have depots in Dunedin, Invercargill and Queenstown.
Mr Tulloch said his company would continue to operate rural, interisland livestock and logging divisions, as well as its North Island freighting company, Retko.
The freight business had grown beyond the ability of his family to manage easily, and needed a corporate structure, he said.
"We had an approach and for family reasons we decided it's a huge workload which had grown too big from our family perspective to run."
Mr Tulloch could not say how many trucks were involved in the sale, but the company's website said it employed 220 staff and operated 240 vehicles, machinery and trailers.
Transport Investments Ltd is based in New Plymouth and operates 1000 trucks under several operators, including Hooker Pacific and TNL.
Both Tulloch Transport and TNL have long histories.
Tullochs was founded by Mr Tulloch's father Mac in 1945 and TNL in 1938 through a merger of several transport operators in Nelson and Marlborough.
Later TNL became part of the Newman's Group, then Transpac Holding before being privatised in 1989.
It remains a privately owned and operated New Zealand company.
