The theatre of Nikopolis is the first monument observed by the visitor coming from the north. It lies in Proasteio, at the north of the fortified city, to the southeast of the monument of Augustus and to the east of the stadion. An impressive construction erected in the early first century AD together with other city buildings, it operated mainly during the religious celebration of Nea Aktia in honour of Apollo. Lists of winners in the Nea Aktia contests found in the temple of Apollo inform of competing poets, sophists, comedians, heralds, trumpeters, guitarists, announcers, pipers and mimes.

The theatre was built on the slope of a hill. In an effort to increase protection from earthquakes, a high buttressed wall was curved around the cavea. A wide corridor called diazoma divided the cavea into two sections, the main theatre and the epitheatro. At the corridor's ends were two large vaulted entrances. The outer protective wall had two stairways permitting spectators coming from the sanctuary of Apollo to access their seats. The cavea supported a peripheral portico probably sheltering spectators in case of a sudden storm. Only the pillars that propped up the roof remain of this gallery. The brick seats of the cavea were destroyed; the proedria (the first row of honour seats) was made of stone. Both the orchestra and the cavea were shaped as a regular semi-circle. There was a high, probably two-storey scene (characteristic of the Roman architecture) with three arched entrances at the fa?ade, communicating with the logeio (the platform between the scene proper and the orchestra where actors performed).

In recent years, works of fixing were undertaken at the monument, concerning particularly the scene walls and the pillars of the portico over the epitheatro.