This paper presents an experimental investigation on the application of textile-reinforced mortar (TRM) layers as a means of increasing the flexural capacity of two-way reinforced concrete (RC) slabs with cut openings. The investigated parameters included the number of TRM layers (one versus two layers), the textile type (two carbon fiber textiles with different weight and geometry), the strengthening configuration (full coverage versus partial coverage via the use of diagonal strips), and the role of the matrix material (mortar versus epoxy resin). For this purpose, six large-scale two-way RC slabs with a central opening were constructed and tested to failure under monotonic loading distributed at four points. It was mainly concluded that TRM substantially enhanced the flexural capacity of the two-way RC slabs with a central cut opening and restored the original capacity of the slab without the opening. The effect of the various investigated parameters is discussed in terms of flexural capacity, post-yielding stiffness, and load resistance at the serviceability limit state. Finally, an already available simple design tool was refined based on the new results of this study. It was found to provide a good estimation of the flexural moment of resistance of the TRM-retrofitted slabs.