The advancement of wireless communication technology is growing very fast. For next-generation communication systems (like 5G mobile services), wider bandwidth, high gain, and small-size antennas are very much needed. Moreover, it is expected that the next-generation mobile system will also support satellite technology. Therefore, this paper proposes a slotted star-shaped dual-band patch antenna that can be used for the integrated services of satellite communication and 5G mobile services whose overall dimension is 15×14×1.6 mm3. The proposed antenna operates from 18.764 GHz to 19.775 GHz for K-band satellite communication and 27.122 GHz to 29.283 GHz for 5G (mmWave) mobile services. The resonance frequencies of the proposed antenna are 19.28 GHz and 28.07 GHz having bandwidths of 1.011 GHz and 2.161 GHz, respectively. Moreover, the proposed dual-band patch antenna has a maximum radiation efficiency of 76.178% and a maximum gain of 7.596 dB.