The aircraft entered service in November 1914, mostly conducting maritime patrols over the North Sea and the English Channel, and played a small role in the Raid on Cuxhaven the following month.

One aircraft made the type's first reconnaissance of the English coast on 25 December; engine problems forced a emergency landing in the Thames Estuary after having flown over Gravesend, Chatham, and having dropped a pair of 5 kg (11 lb) bombs over Sheerness to no effect.

Unable to take off because of damaged floats, the aircraft taxied across the North Sea for hours before exhausting its fuel and finally drifting ashore near German-controlled Wenduine, Belgium.

A FF.19 on patrol spotted the Harwich Force after they had flown off their aircraft and begun to move westward and had to return to Heligoland to deliver its report since it lacked a radio.

While it is unknown if he took any shots at the enemy aircraft, the Blériot had engine problems over the port and was forced to make an emergency landing and was captured intact.

The captain of SM U-12, Lieutenant (Kapitänleutnant) Walther Forstmann, submerged his boat just enough to allow the FF.29 to taxi over his forward hull and then blew his ballast tanks to raise the floatplane out of the water.

The water was choppy enough that after an hour's steaming the pilot, Lieutenant (Oberleutnant zur See) Friedrich von Arnauld de la Perière, and Forstmann were worried that the FF.29's floats would be damaged, so they decided to cut the mission short and U-12 submerged so the floatplane could conduct its intended reconnaissance of the Kentish coast.

The following day, while returning from a reconnaissance patrol over the English Channel and bombing some paddle steamers at Dunkirk, the crew of a FF.29 got disoriented and landed in Dutch territorial waters near Terneuzen.

[9] On the first day of May, two FF.29s spotted four British trawlers near the Noordhinder Bank, north of Ostend, but the engine of one of the floatplanes broke a crankshaft and it had to land.

The floatplane still flying had to return to base for repairs and dropped a message to a pair of torpedo boats giving the downed FF.29's location.

Two FF.29s took off to investigate the strength of the attacking force and the surviving destroyer broke off its rescue efforts and left the scene when it spotted the floatplanes.

[11] A FF.29 was interned by the Dutch on 21 November 1915; the aircraft received the serial number S-1 when the Netherlands Naval Aviation Service was formed in 1917.

It was disassembled for use as a pattern aircraft and a copy was built as the Mågen 17 by the Airplane Construction Shop of the Naval Shipyard (Orlogsværftet Flyvemaskineværksted).

[14] FF.29A: Twelve aircraft built by Kaiserliche Werft Wilhelmshaven with a 100 PS (74 kW) Mercedes D.I engine and modified floats and tail surfaces.