Yes, the safety used as a food additive has been approved by the U.S. Food and Drug Administration (FDA), European Food Safety Authority (EFSA),  Joint FAO/WHO Expert Committee on Food Additives (JECFA), as well as other authorities.

FDA
May be safely used as a general-purpose sweetener and flavor enhancer in foods. (6)

EFSA

Acesulfame potassium E950 is listed in Commission Regulation (EU) No 231/2012 as an authorised food additive and categorized as “sweeteners” (7).

Authorised Uses And Use Levels
It is listed in a lot of food applications with the maximum usage ranges from 25mg/kg (in beer) to “quantum satis” (in table-top sweeteners). The following energy-reduced or no sugar products may contain it(8):

Jams jellies and marmalades
Sauces
Spreads
Cocoa and Chocolate products
Chewing gum
Ice cream
Table-top sweeteners
Dietary foods for weight control diets  
Flavoured drinks
Desserts
Fine bakery wares
UK Food Standards Agency
Categorized in “Sweeteners” (9)

Food Standards Australia New Zealand
In Australia and New Zealand are all with the code number 950. (10)

JECFA
Functional Class: food additives, flavour enhancer, sweetener. (11)

Acceptable daily intake: ADI “15 mg/kg bw” set in 1990. (12)

http://www.chinafooding.com/Acesulfame-K