The multi-million rand factory - which started operations on March 15 - was built by JSE-listed construction group Murray & Roberts, the IDZ said in a statement on Wednesday.
The R18 million reinforcing steel construction plant was expected to create several employment opportunities.
According to the plant's manager, Nick Lotter, the East London IDZ was the ideal place for the factory.
"Basically the East London IDZ has a good piece of level ground which made practical sense.
"It's also a closed secure environment."
Lotter said East London was a strategic growth point.
"We are also close to the former Transkei where infrastructure development is needed."
He said that the plant was already functional and just needed "a few finishing touches".
East London IDZ sector manager Zwelethu Mhlophe said the factory was critical for the region as it would develop steel for reinforced concrete columns to be used in construction projects in the Eastern Cape.
"This is another investment by the East London IDZ and means new jobs will be created," Mhlophe said.
Border Kei Chamber of Business managing director Les Holbrook said of all the development nodes and zones in South Africa, the East London IDZ was proving to be "the best, most efficient and cost effective location for new investment".
He said the jobs created and the contribution to the local fiscus would be invaluable and go a long way to helping with the massive economic backlogs.