The first written reference to Zletovo comes from the charter of the Byzantine Emperor Basileios II for the archiepiscopal see of Ōhrid from the year 1019. Zletovo (καὶ τὴν Σθλετοβὰν) is listed as part of the Bishopric of Morozvizd (Morobisdos). The Saint Gavrilo Lesnovski departed for the Lěsnovo Monastery (vь monastirь Lesnovskyj), from which he was released after a probationary period with the blessing of the abbot to enter a hermitage near the monastery and Zletovo (za nekoj skïtь blizь prjamo manastirь, vь dolь prjamo Zletovo). According to the Vita, the Saint Gavrilo Lesnovski also came to the aid of a local Bulgarian prince named Mihail in the fight against the Pechenegs and Cumans. Mihail had to flee from his opponents to Ratkovica (vo stranu Ratkovicu). He was able with the assistance of the saint to sidle up to the opposing general Mavragan near Rataica in Zletovo (u Slětovo) and to kill him (u Rataicě i ubi Mavragana). Zletovo was withdrawn from the sovereign authority of the Byzantine Empire in 1282/1283 during the reign of the Serbian King Stefan Uroš II Milutin (i Zletovu). Zletovo is mentioned in the charter of the Serbian King Stefan Uroš II Milutin for the Gračanica Monastery from 1315 (or 1321?) (i po Zletovoi). The scribe Stanislavь completed in 1330 a Slavic manuscript in the Monastery of Saint Michael the Archangel in the mountains of Lěsnovo, which was in the domain of Ovče Pole and the region of Zletovo (vь ōblasti ōvčepolьskoi vь horě zljętovstěi, v gorě lěsnovьstěi, v monastiri stgo arhistratiga Mihaila). The scribe Stanislavь finished his prologue of the manuscript in the time, when Dragoslavь ruled over the land of Zletovo as Župan (ōbdrьžjaštu horoję Zlętovьskoję županu Dra’goslavu). According to the Slavic founding inscription for the Lěsnovo monastery from 1340/41, the monastery received annualy 100 perpers from the revenue of the market in Zletovo (ōd zletovьskago trьga na godine sto perperь). The same inscription mentions the vineyards of the town of Zletovo (nadь gьrdsko lozie). However, Zletovo with its urban metochion was not included in the endowment for the Lěsnovo Monastery in 1340/41, 1346/47, or 1381. The scribe Stanislavь copied a Menaion at the request of Jovan Oliver destined for the Monastery of the Saint Michael the Archangel in Lěsnovo in 1342 in Zletovo according to the colophon of the manuscript written in Slavic language (vь horě Zletovcěi). In the founding charter of the Serbian Emperor Stefan Uroš IV. Dušan for the Eparchy of Zletovo with its seat in the Monastery Lěsnovo from the year 1346/47 the erection of the monastery by the Serbian Espot Jovan Oliver is mentioned. Jovan Oliver built a church in honor of the Holy Archangels Michael and Gabriel in the Zletovo region in Lěsnovo (sьzdati jemu hramь vь ime velikoslavnyhь i besplьtnyihь činonačelnikьь arhistratiga Mihaila i Gabrïila, vь straně že zletovьscěi rekomōje Lěsnovo; crьkvi Arhanggelu u Zletovoi; crьkvi Arhanggelu u Zletovoi). Zletovo appears in the boundary description of the hamlet/village Globica in the founding charter of the Serbian Emperor Stefan Uroš IV. Dušan for the Eparchy of Zletovo with its seat in the Monastery Lěsnovo from the year 1346/47 (i što se kь Zletovoi kami vali tozi Zletovu budi a što se kь Globici vali tozi crьkvьno). In addition, the charter confirms the annual revenue of 100 perpers from the market in Zletovo for the Eparchy of Zletovo with its seat in the Monastery Lěsnovo (ōtь zletovьskago trьga). The Bishopric of Zletovo (episkopi zletovьskoi) owned also possessions in Pianitza according to the same charter. A note in the Slavic manuscript Lesnovski parenesis relates that it was written in Zletovo at the place called Lěsnovo in the Monastery of the Holy Archangel Michael in 1353 (vь zemli zljatovsьskoi, vь městě rekoměmь Lěsnovo, vь ōbiteli svetago arhistratiga Mihaila), as Arsenije was the Bishop of Zletovo. In 1354/55 the Serbian Emperor Stefan Uroš IV Dušan gave permission to his nobleman Vlatko Paskačić to donate the Church of Sveti Nikola in Psača, which Vlatko had erected on the inherited property of his father, together with the appertaining metochion to the Monastery of Hilandar (I vьspomenu carstvu mi prěvьzljubljenʼny i pravověrnii vlastelinь carstva mi Vladko ō crьkvy svetago Nikoly jaže jestь sьzdalь na svoōi baštině Pʼsači a sь blagoslovljenijemь carstva mi...i poljubi prěd carstvomʼ mi i priloži svoju baštinu crьkvь svetago Nikoli na Psači prěsvetěi Bogorodici hilandarьskoi sь vsěmь metehōmь). Stefan Uroš IV Dušan enlarged Vlatko's endowment with land near Krilatica, where a certain Neōr had resided and where the Emperor had moved miners from Zletovo (I na Krilatici zemlja koja jestь ōt Trnov’ca na čimь jestь sědělь Neōrь, posadi rudare koje prěseli ōt Zljetove). The Eparchy of Zletovo was probably abolished around 1370. After 1376/77, the Serbian Despot Jovan Dragaš (Ioannes Dragases) and his brother Konstantin Dragaš (Konstantinos Dragases) confirmed that the Monastery Hagios Panteleemon on the Holy Mount Athos possessed the churches of Saint Dimitrije and Saint Nikola in Zletovo (u Zletove stgo Dimitrïa, i svety Nikola). The Serbian local ruler Konstantin Dragaš confirmed on the 15th August 1381 that the Hilandar Monastery had the right to become the annual revenue of 100 perpers from the market in Zletovo aimed for the Lěsnovo Monastery (I ōd trьga zlětovьskoga da uzima Arhanggelь lěsnovьski na vsako gōdište r. Perьperь, jakože pišetь u hrisovuli carskomь). A forged charter from the 15th century, also known as the charter of the Serbian King Stefan Uroš II Milutin concerning the settlement site Ulijare settlement from 1318, relates, among other things, about the conquest of Zletovo by the Serbian King Stefan Uroš II Milutin between the years 1282 and 1284 (Zletovu). The Lěsnovo Monastery is registered in the Defter for the Sanjak Köstendil from 1570 to 1572 as Arhangel. The Lěsnovo Monastery possessed in Zletovo five watermills. Zletovo appears also in the Defter for the Sanjak Köstendil from 1570 to 1572 as as Izltva.