Horacio Dela Costa High School began its journey as a secondary educational institution when under the administration of Hon. Atty Enrico Echiverri as the Caloocan City Mayor, the city engineer’s office received a deed of donation dated July 17, 2005 and consequently, on July 22, 2005, the mayor’s office received the deed.  It was made by the non-stock and non-profit organization of FREEDOM TO BUILD, INC., represented by its executive director William J. Keyes.

            The deed of donation contained the agreement of turnover of development of the parcels of land located and known as Horacio Dela Costa Homes II to the City of Caloocan.

            The deed gave responsibility to the city to develop the said area for the benefit of the residents and the constituents of the city.

            Block 7 Lot 3 Phase 2 of the Horacio Dela Costa Homes II became the location of new building that was constructed under the administration who received the deed of donation. From the humble beginning of two-storey building with 8 classrooms and with no school fence, the school began its operation under Horacio Dela Costa Elementary School with Mrs. Evangeline A. Ngohayon’s administration, the school principal, in 2006. Chairs, tables and blackboards were borrowed from the elementary school together with the 3 pioneered teachers namely Mrs. Aida B. Maguddayao, Ms. Rizalina C. Castro and Mr. Carlito Z. Carual who taught the first batch of students of the school.

A year after, the school’s operation was transferred to Amparo High School, thus the name Amparo High School Annex was given to the school.  It catered now first year and second year high school on its second year of operation.  It was able to produce its first batch of graduates in year 2010 under the care of Dr. Nellie D. Salvador, Head Teacher, from Amparo High School, principalship passer and Officer-In-Charge.

            Year 2011 saw the addition of two more floors over the 2-story structure, making it the highest and biggest building within 2 kilometer radius.  Added to it is the 8-feet perimeter wall enclosing the parameters of the school, making it exclusive as a campus.  By then, it was fully operational as the AHS-Horacio dela Costa Annex that had a complete set year levels from the freshmen to seniors. This school year gave the AHS-Horacio dela Costa Annex 16 permanent teachers from all the eight departments headed by Mrs. Socorro DG. Claveria as Officer-In-Charge.  Like her predecessor, she is a Head Teacher from Amparo High School.  Together with the mostly first timer public school teachers, she designated the offices whoever she deemed fit to take over ancillary functions.  Of the 16 classrooms, one served as the principal’s office and at the same time a faculty and receiving room.  Another room served as library and computer laboratory.  Eleven classrooms were used for one-shift classes.  The three remaining unused classrooms and the top floor served as convertible program hall for monthly activities that needed big area.  From a student body of over four hundred from the previous year, it reached over seven hundred.

            Among the 16 faculty members, coordinators, advisers and ancillary services functions were assigned to take responsibility over the subjects and matters that pertain to the school.

            This school year holds the record of the annex school having the Parents and Teachers Association creating a resolution for the recognition of the independency of the school.  Along with it are the Horacio Dela Costa Homeowners Association and several more endorsements from the local government.

            As of the writing of this, the AHS-Horacio Dela Costa Annex  have gone through two principals of Amparo High School, Mrs. Josefina Aquino and Mrs. Milagros Austria respectively, and two OIC Schools Division Superintendent, Mrs. Corazon Gonzales and Mrs. Rita E. Riddle respectively. Officers-in-Charge assigned to the annex school mainly were Head Teachers from the mother, Amparo High School.  Mrs. Rizalina Bueno was the first OIC who is not from Amparo High.  She took helm of the annex school in the school year 2013. 

            The first ever school papers Dela Costan (for the Filipino Department) and the first Perspective (for the English) released their first issues.  At the same time, the schools experience its first participation to the press conference competitions. The 7th of February 2014 saw the first ever celebration of the Foundation Anniversary of the school.  It was celebrated with a massive ground demonstration participated by all year levels and managed by the MAPEH Department.  The turn of Mrs. Bueno gave rise to the school greetings “Good HDLC Morning/Afternoon” with the acronym representing Honest, Discipline and Law Abiding Citizens.  Her term saw the growth of the faculty from 20 to 32 strong faculties.  With the eight classes represented, the faculty members under her term, the OCA MALAPITAN Building started its construction.  Also, the previous Amparo High School Annex lettering imposed on the façade of the building was symbolically removed signifying the move from annex to an independent high school on November 2014.