The Gesta Comitum Barcinonensium names (in order) "Radulfum, Guiffredum, Mironem et Suniarium" as the four sons of "Guiffredus Pilosus comes" & his wife, specifying that Sunyer succeeded his father "in comitatu Urgelli et fuit primus comes Urgelli".
He succeeded his father jointly with his brother in 897 as Comte de Barcelona, Girona i Osona, and his brother in 911 as sole Comte de Barcelona, Girona i Osona. “Idelxerus episcopus, Garsendis comitissa, Suniarius comes et marchio, Ermemirus vicecomes”, as executors of “Wifredo comite quondam filius fuit de Wifredo comite quondam”, executed the testament of the deceased by charter dated 1 Dec 911. A charter dated 16 May 914 records the allegiance of the inhabitants of San Juan, Ogasa, Surroca and Caballera del valle de Ripoll to the abbess of Ripoll Sant Joan, in the presence of "Mirone et Suniario comites et marchiones, Ermemiro et Unifredo vicecomites". “Garsinde comitissa Suniarius comes et Ermemirus vicecomes”, as executors of “condam Guifredi comiti...Borelo”, donated “in comitatu Ausona in terminis de Felgeirolas et de villa Oligo” to Sant Joan de Ripoll by charter dated 9 Sep 916. “Suniarius...comes et marchio et uxor mea Richildes” donated property to Sant Salvador de Ripoll, for the souls of “genitorum meorum condam Wifredi comiti et Widinildi simulque et fratre me condam Wifredi comiti atque sorori mee condam Richildi”, by charter dated 25 Mar 925. “Suniarius…comes et Marchio” donated property to the church of Girona, for the souls of “patri meo Wifredi quondam, vel fratri meo Wifredi quondam…vel filio meo Borrello”, by charter dated 23 Nov 934. Faced with Muslim attacks along the coast at Maresme and Empordà, comte Sunyer launched a counter-attack in 936 which was halted by Ahmad bin Muhammad bin Ilyas who led the siege of Zaragoza. “Dompnus comes Suniarius et marchioni...vel eius...prolis dompnus Ermengaudus Ausonensis comes” dedicated the church of Santa Maria de Moià by charter dated 23 Aug 939. Caliph Abd Al-Rahman III made peace with comte Sunyer in 940. “Suniarius comes et marchio” donated property “in comitatu Ausona in apendicio de castro Veltregano in loco...Palacio”, which “advenit mihi...ex comparacione...de fratri meo Radulfo qui fuit quondam vel de filio eius Oliba”, to Santa Maria de Ripoll, for the sins of “filio meo Ermengaudo defuncto”, by charter dated 6 Sep 943. “Soniarius comes ac marchio et uxor mea Richildis comitissa” donated donated property “in comitatu Gerundensi in appendicio sancti Martini in villare...Rivofredo” to the church of Girona, for the souls of “fratris mei quondam Borelli et filii mei quondam Ermengodi”, by charter dated 16 May 944, subscribed by “Audegarius vicecomes...”. “Suniarius comes ac marchius et uxor mea Richildes comitissa” donated donated property to the church of Barcelona, for the souls of “patri meo condam qui fuit Guifredi comitis et matri mea condam qui fuit Guidinillis comitissa et fratri meo qui fuit condam Borrello comites...et proles meos condam Ermengadus et Borrellus”, by charter dated 16 May 944. "Suniarius comes et marchio" donated property "in comitatu Gerundensis in locum…villa Felgars" to Saint-Pierre de Rosas by charter dated 25 Jun 945. "Suniarius comes et coniux mea Rechellis comitissa" donated property to the monastery of Santa Cecilia de Montserrat by charter dated 31 Jul 945.
He succeeded his brother Seniofredo in 948 as Comte de Urgell. "Soniarius comes" donated property to the monastery of Grasse by charter dated 30 Jun 953, witnessed by "Isarni comitis…".
The martirilogio of Vic records the death "Id Oct" of "Suniarius". The year of his death is narrowed to 954 given the charter dated 19 Feb 955 under which his son Comte Borrell granted property, acquired from "su difunto padre el conde Suniario", to his cousin Miró. The Gesta Comitum Barcinonensium the death in 950 of "Sunyer" and his burial "in monasterio Rivipolli". 2