The United States received its first C-27J on 25 September 2008. In September 2008, L-3 Link's C-27J schoolhouse officially began classes at the Georgia Army National Guard Flight Facility, Robins Air Force Base, Georgia. By April 2009, the U.S. Army had accepted deliveries of two aircraft and had 11 more on order. In May 2009, the U.S. Army/Army National Guard relinquished all aircraft to the U.S. Air Force, primarily the Air National Guard, this led to the purchase being reduced to 38 C-27s and the USAF receiving total control of all US C-27Js. Initially, the C-27J to be operated by the Air National Guard for direct support of the United States Army, later both Army National Guard and Air National Guard flight crews support the aircraft's fielding. By July 2010, the U.S. Air National Guard had received four C-27Js for testing and training, initial operational capability was then expected in October 2010.
The U.S. Air Force performed the C-27J's first combat deployment in Summer 2011. In August 2011, two C-27Js flown by Air National Guard aircrews, augmented with Army National Guard personnel, began operations at Kandahar Air Field, Afghanistan. Between August 2011 and June 2012, the C-27Js of the 179th Airlift Wing, followed by the 175th Wing executed more than 3200 missions transporting over 25,000 passengers, and 1400 tons of cargo. Via tactical control of the C-27Js, the U.S. Army was able to employ helicopters more efficiently, splitting missions between the two platforms based on their relative strengths.
On 26 January 2012, the Department of Defense announced plans to retire all 38 USAF C-27Js on order due to excess intratheater airlift capacity and budgetary pressures; its duties are to be met by the C-130. In February 2012, Alenia warned that it would not provide support for C-27Js resold by the US to international customers in competition with future orders. On 23 March 2012, the USAF announced the C-27J's retirement in fiscal year 2013 after determining other program's budgetary needs and requirement changes for a new Pacific strategy. The cut was opposed by the Air National Guard and by various legislators.
In July 2012 the USAF suspended flight operations following a flight control system failure. By 2013, newly built C-27Js were being sent directly to the Davis–Monthan Air Force Base boneyard. The USAF spent $567 million on 21 C-27Js since 2007, with 16 delivered by the end of September 2013; 12 had been taken out of service while a further five were to be built by April 2014 as they were too near completion to be worth cancelling. Budget cuts motivated the divesture; a C-27J allegedly costs $308 million over its lifespan in comparison with a C-130's $213 million 25-year lifespan cost.
In November 2012, the C-27J deployed for its first domestic mission, contributing to the Hurricane Sandy relief effort.
In July 2013, the U.S. Coast Guard was considered acquiring up to 14 of the 21 retired C-27Js and converting them for search-and-rescue missions, while cancelling undelivered orders for the HC-144 Ocean Sentry to save $500–$800 million. EADS claimed that the HC-144 costs half as much as the C-27J to maintain and operate. The U.S. Forest Service also wanted 7 C-27Js for aerial firefighting. The U.S. Special Operations Command (SOCOM) were interested in acquiring ex-USAF C-27Js. If the DoD determined it could not afford the aircraft, they would go to the Forest Service. In late 2013, SOCOM was allocated 7 C-27Js to replace its CASA 212 training aircraft. In December 2013, the 14 remaining C-27Js were transferred to the Coast Guard.
In October 2006, Italy accepted delivery of the first C-27J of an initial batch of 12 aircraft. From 12 September 2008 to 27 January 2009, a pair of Italian Air Force C-27Js were deployed to Afghanistan to contribute to NATO in-theatre airlift operations. In December 2013, an Italian C-27J was deployed to the Philippines to participate in international humanitarian relief operations in the aftermath of Typhoon Haiyan. The Italian Air Force is also the launch customer for the MC-27J, an armed gunship variant of the C-27J; Italy is the first European nation to operate such an aircraft.
In December 2011, the Royal Australian Air Force issued a Foreign Military Sales request for 10 C-27Js valued at US$950m to replace its retired DHC-4 Caribou fleet. Australia had opted for the C-27J over the rival C-295 following an RAAF evaluation, which had noted the C-27J's wider and taller cabin being compatible with the Australian Army's general purpose G-Wagon vehicle, and palletized goods. In December 2013, the first Australian C-27J performed its maiden flight. In December 2014, the RAAF began maintenance training on the type; delivery of the first two of the ten C-27Js on order was also formally accepted that month.
In 2006, Bulgaria had initially ordered five C-27J to replace its aging fleet of Antonov An-26 aircraft, but reduced its order to three aircraft in 2010 due to funding shortages. In March 2011, the Bulgarian Air Force received the third and final of the C-27Js ordered; the fleet is employed for military transport missions as well as medical evacuations, special tasks of the Interior Ministry, and participating in international operations such as the rotation of Bulgarian troops in Afghanistan.
On 6 July 2011, the Mexican Air Force signed a $200 million contract for four C-27Js and a multiyear support agreement for the fleet. The first aircraft was received two months later, all four were delivered by the end of 2012. Mexico's C-27Js are based at Santa Lucía Air Force Base Num 1 and operated by 302 Air Squadron alongside a number of C-130 Hercules.
In June 2013, the Peruvian Air Force was negotiating to acquire four C-27Js for $200 million; future purchases by Peru may increase the total to 12 Spartans. The C-27J competed against the EADS CASA C-295, Antonov An-70, Antonov An-32, and C-130J. On 25 November 2013, Peru selected the C-27J; two aircraft and associated support was purchased in an 100 million-euro deal. On 27 March 2015, the first C-27J was formally accepted by the Peruvian Air Force; by this point a total of four C-27Js were on order for the service.
In 2006, the Romanian government announced the selection of the C-27J, seeking 7 aircraft to be delivered from 2008 to replace Antonov An-24 and Antonov An-26 aircraft, beating the EADS CASA C-295. In February 2007, a legal challenge filed by EADS blocked the Romanian order; the order was allowed to proceed when the Romanian court rejected EADS' complaint in June 2007. On 7 December 2007, a contract for the seven C-27Js was officially signed. On 12 April 2010, the first two C-27s were delivered to the Romanian Air Force.
In 2007, the C-27J was being considered as a sole-source C$3 billion contract by Canada as a future replacement for its current search and rescue air fleet.
Slovakia's air force has selected the C-27J and is negotiating an order for at least two aircraft.
The Indian Air Force has issued a Request for Information (RFI) for 16 medium military transport aircraft. Alenia Aeronautica responded with information about the C-27J.
On 21 August 2009, Taiwan announced that it had entered price negotiations with Alenia Aeronautica for the sale of six C-27J Spartan aircraft. Indonesia is considering the purchase of the C-27J as of March 2011.
The C-27J has been shortlisted as a candidate for the Philippine Air Force (PAF) medium lift aircraft program. A joint team from the Philippines' Department of National Defense (DND) and PAF inspected the C-27J in January 2012. The DND already received approval from the Philippine president to purchase 3 units, and is awaiting congressional approval as of November 2012.
In 2015, Alenia Aermacchi were studying the development of a maritime patrol variant of the C-27J. Other proposed variants of the platform include a multi-mission C-27J that could be armed with various air-launched weapons and equipped with a maritime surveillance radar; Alenia Aermacchi have promoted this model to the Royal Air Force.