The Alwi Mosque is located in Kangar, the capital of Perlis, the northernmost state in peninsular Malaysia. The mosque is the oldest mosque in Perlis and could be a previous state mosque that was built amid the British Colonial period.

Its unique feature, the onion-shaped dome, bear resemblance to other colonial mosques in the country such as the Zahir Mosque in Alor Setar and the Kapitan Keling Mosque in Penang. The main dome sits on an octagonal drum, with series of rounded windows on the perimeter and culminates with a crescent finial at the top.

Another distinct feature of Alwi Mosque is the typical Mughal-styled minaret with a chattri styled balcony and capped with a pointed onion-shaped dome. Several mini onion-shaped domes at the front and side entrances complete the influence of Mughal Architecture to the mosque.

The Alwi Mosque is aligned facing the Jalan Kangar-Alor Setar road. Its rectangular layout is primarily covered with a slight pitch flat roof form and partly covered by a high parapet wall decorated with triangular crenellations.

The main entrance porch prominently featured pointed arches and onion-shaped mini dome. An ornately carved concrete balustrade across the porch roof and two attached obelisks like structure or turrets at each corner complete the ensemble of a classic Mughal Architecture.

The main prayer hall is demarcated by eight sided pointed arches that allow natural daylight to permeate through the arched openings. An imposing onion-shaped dome hovers above the main prayer hall.

The mihrab niche to the right of the main prayer hall, is manifested through four round columns and a round-shaped arch. An elevated mimbar pulpit where the Imam delivers his sermon, sits to the right of the mihrab.