In the last decade of 19th century, two Kudippallikoodangal were working at chellanam. The owners of these schools were convened by the then Bishop of Cochin and they decided to merge these two Kudippallikoodangal into one. The new school was named St. Mary's LPS, Chellanam and it came under the management of St. Sebastian's Church Chellanam. The first manager was Rev. Fr Kadeparambil, the vicar of the Parish. After nearly 10 years a branch school was opened at Maruvakkadu. In 1924, the school was upgraded into an upper primary school and Rev. Fr. George Herden was the Manager. Later in 1948, the school was upgraded to High school. Since then the school has played a prominent role for the development of the coastal area. The school at present functions in a beautiful three-storied building constructed when Rev Fr Thomas Parathara was the General Manager of the School. Our institution is always blessed with excellent heads of the institution. Our esteemed genre of HMs begins with Shri Rapheal the first Headmaster.

St. Mary’s HS, Chellanam is an esteemed institution which comes under the Sub District of Mattancherry. We are proud to have a unit of NCC and KCSL in our school. We also have an active Safety club , Health Club, Harithasenaand, an Antidrug unit functioning successfully in our school. We have arranged a well equipped Computer Lab , a Smart Room and a Science Lab for our children. Our school is running in a grand new building with girls friendly toilets. To make the journey more comfortable for our students we have an school bus .We have very efficient Physical Education teachers to provide training for Football, Handball, Hockey, Kho Kho , Kabadi , Lawn Tennis, Table Tennis , Shuttle Badminton, Volley ball, Basket ball, Throw Ball, Swimming and Athletics. Martial arts like Taekwondo is also trained here.

We have achieved 98% pass in 2010-11 SSLC. A weekly check up for the students is ensured by the school as it situated in coastal area. Our children had secured first prize with A grade in ‘Parichamuttukali’ in the sub district Youth Festival .With the active participation of the members of Harithasena we have grown vegetable garden, plantains and started paddy cultivation in the school premises and in their homes. Our students had taken part in the sate level work experience the spot event of net making competition.

In sports our school had achieved an outstanding place in the sub district. Our school have produced many district and state players. We were sub district champions in football , shuttle badminton , lawn tennis, taekwondo and swimming. We were the runner up in Kho Kho, hockey, Table tennis, and Handball. The school renders laudable service in this land of fisherman and farmers. It has moulded many eminent personalities who has proven their talent both in India and abroad and we strongly believe that it will prove its worth in future too.