Combat is a core mechanic of Star Trek Online across space and ground maps. The game is rare in having both a fully-fledged space and ground combat system throughout the game. A player's equipment contributes to their effectiveness and hence the ease of their progression through a mission.
- Main article: Space combat
Space combat occurs on system maps (i.e. local maps, not Sector Space) between starships or other armed space-faring objects or beings. Combat only occurs within 10km and while engaged, abilities such as Full Impulse and, in some cases, cloaking are locked out.
A starships offensive capabilities come largely in the form of ship weapons (i.e. phasers or torpedoes). These face off against defensive capabilities such as Ship Shields and hull. But beyond those, all ship systems have a bearing on the combat efficiency of your ship with Impulse Engines adding to your manoeuvrability and hangar pets providing tactical support.
- Main article: Ground combat
Ground combat can occur on any ground map outside of hubs and the player is usually aided by their bridge officers. The player can use automatic tab or manual targeting in combat, per their preference.
Like their captain, bridge officers have to be equipped with weapons, armor and shields. As well as the common ranged weapons, captains and officers can also use melee weapons in combat as well as a number of devices. However, only captains have access to kits.