Direct proof of use
In August 2015, the Washington Institute for Near East Policy reported that Houthi forces in Yemen already fielded Iranian-supplied anti-tank systems including the Metis-M, Kornet-E, and RPG-29. The report placed that fielding in the southern campaign after Houthi-Saleh forces had overrun Aden and then lost the city to Hadi-aligned and coalition-backed forces.
The same source described the RPG-29 as part of a portable anti-tank weapons problem for the Saudi-led coalition, but it did not identify a dated RPG-29 firing incident or a specific vehicle hit. The strongest public claim for this conflict is therefore fielding by Houthi-aligned forces, not a confirmed individual engagement.
Sources: The Saudi-UAE War Effort in Yemen (Part 1)
Timeline
Washington Institute reporting from July 2010 said open-source video of Houthi rebel fighters appeared to show advanced RPG-29 warheads before the later civil-war phase. That earlier reference supports prewar Houthi exposure to RPG-29-family munitions, while the August 2015 report is the source that places RPG-29 fielding inside the 2014 Yemen Civil War.
By March 2015, Houthi-Saleh forces had advanced into Aden. After the Saudi-led coalition and southern forces retook the city in July 2015, the Washington Institute assessed that Houthi forces could still reinforce southern defenses with Iranian help and already had RPG-29s among several newer anti-tank systems.
Sources: Yemen's Forever War, The Saudi-UAE War Effort in Yemen (Part 1)
Narrative
The RPG-29 fit a Houthi-aligned ground force that relied on small, dispersed defensive teams, cached weapons, mines, recoilless rifles, mortars, and anti-tank guided missiles to hold terrain under coalition air superiority. Combating Terrorism Center analysis of the Houthi war machine describes Houthi tactical groups linking up with weapons near the front and using anti-tank weapons from defensive positions.
Within that pattern, the RPG-29 was a close-range anti-armor and fortification-attack weapon rather than a missile or long-range strike system. The available public sourcing does not establish quantities, serial provenance, or a named battlefield incident in Yemen, but it does directly support Houthi-aligned fielding during the war and background evidence that the movement had displayed RPG-29-related weapons before the 2014 civil-war phase.
Sources: The Houthi War Machine, Yemen's Forever War, The Saudi-UAE War Effort in Yemen (Part 1)