Theridion ampliatum is a species of Theridiidae that is endemic to New Zealand.
This species was described in 1892 by Arthur Urquhart from a female specimen. It was redescribed in 1935.
The female is recorded at 3.8mm in length. The cephalothorax is coloured orange ochreous. The legs are creamy ochreous. The abdomen is yellowish olive green and is covered in flecks.
This species is only known from Stratford, New Zealand.
Under the New Zealand Threat Classification System, this species is listed as "Not Threatened".