Well… it depends what you mean by “an equivalent to Beowulf”!
If you mean an early medieval narrative poem featuring a warrior hero battling monsters set in pseudo-historical pre-monotheistic times—yes, there are many of those. Probably the most prominent belong to the “Persian Epic Cycle,” New Persian poems about the exploits of pre-Islamic Iranian heroes. While there were some early innovators during the 10th century CE, the genre didn’t really take off until the Shāhnāma (“Book of Kings,” 1010 CE) of Abolqāsem Ferdowsi. In scope, the Shāhnāma’s 50,000 couplets far exceed Beowulf’s 3000-odd alliterative lines, narrating the reigns of fifty Iranian monarchs from the world’s creation until the Islamic conquests. But some individual sections of the epic bear some resemblance to Beowulf. The Haft Khwān or “Seven Courses'' of the hero Rostam come to mind, a series of adventures in which a strong young champion travels from his homeland, confronts various perils, descends into a gloomy underworld to overcome a monstrous parahuman, and wins great renown from an otherwise hapless monarch. You can find the Warner Brothers’ unabridged, if fairly antiquated, translation of the entire poem for free online (volume 1 is here). Alternately, Dick Davis’s abridged but highly readable translation is widely available, and does contain Rostam’s Haft Khwān. The Shāhnāma is also an “equivalent” of Beowulf in that it is often regarded as the foundational text of Persian literature (though, like Beowulf, it is not actually the oldest work in the language). But whereas English speakers essentially need to learn a whole new language to understand Beowulf’s English, speakers of modern Persian can understand the Shāhnāma with minimal difficulty.
The Shāhnāma spawned numerous imitations and fan-fictions, which tend to focus, like Beowulf, on the career of a single hero. Also like the Old English poem, the Garshāspnāma of Asadi-Tusi (“Book of Garshāsp,” 1066) and Bahmannāma (“Book of Bahman,” c. 1100) both end with a fight against a monstrous reptilian beast. Garshāsp overcomes his monster, only to fall prey to the “celestial dragon” (azhdahā-ye falak) of time/old age; Bahman is ignominiously devoured by his. Neither of these is available in full English translation, though the Garshāspnāma has been published in French. The Kushnāma (also c. 1100) is, like Beowulf, known only from a single, fortuitously preserved manuscript. A translation by Kaveh Hemmat is forthcoming this year.
In Arabic, the closest equivalents are probably the sīrāt, prose folk-epic “biographies” of various heroes. These likewise feature numerous battles against monsters and expeditions to exotic lands. Unlike Beowulf, the sīrāt tend to be tremendously long—often thousands and thousands of pages—and most surviving versions date from the very late medieval or early modern period. Portions of the sīra of Sayf bin Dhī Yazan are available in a good translation from Lena Jayyusi, if you want a taste of this genre.
Is this the kind of thing you’re looking for, or do you mean something else by “equivalent to Beowulf”? I’m happy to provide clarifications and follow-ups!