Arenas ran a successful campaign as a member of the
House of Representatives. She was set to run unopposed in the
2013 elections but gave way to her mother now-Deputy Speaker Rose Marie Arenas. She was the first woman to be elected as Representative of the Third Congressional District of Pangasinan. While in office, she developed numerous infrastructure projects in the Third District, in particular the building of farm-to-market roads, bridges, school buildings and civic centers. During her tenure, agriculture capacity increased after the installation of irrigation systems in 6,000 hectares of farmland. She was responsible for concretising and asphalting more than 30,000 kilometres of road; and the construction of five main bridges that connected different barangays and towns to each other: the San Vicente-Pogo Bridge in the municipality of
Calasiao, Ican-Bugtong Bridge and Pamaranum Bridge in the Municipality of Malasiqui and San Vicente and Calvo Bridges in the Municipality of
Bayambang. She also oversaw the rehabilitation of river banks, construction of proper drainage systems, and clearing waterways to alleviate the District's long-time flooding problem. She was made the chairperson of the House Special Committee on Brunei-Indonesia-Malaysia-Philippines East ASEAN growth Area (BIMP-EAGA) and authored House Bill No. 4363, calling for the creation of the Southern Palawan Special Economic Zone and Freeport Authority to boost economic growth in the East Asean Region. Arenas also authored and sponsored national bills that called for social justice, empowerment of the marginalized, and the improvement of basic services, such as health, education and livelihood. In line with combating corruption in President
Benigno Aquino’s “Daang Matuwid” she authored HB 2471 seeking the protection, security and benefits of
whistleblowers. In the
15th Congress, she would go on to oversee the establishment of a Provincial Information and Communications Technology Hubs (HB 4066), and the creation of a Department of Overseas Workers (HB 4408). She also authored the Service to Pay Act, the house resolution calling for the punishment of grain hoarders, the house bill calling for the creation of a Magna Carta of Agricultural Development Workers, and an act calling for the freezing of prices of basic commodities during calamities. She was also honored as the Most Outstanding Congresswoman of 2007, during her first term in the House of Representatives. Arenas was nominated as one of the Ten Outstanding Young Men and Women (TOYM) of 2011. In 2013, she launched a project, the Education Leadership Training in partnership with the
Foothill College of Silicon Valley which provided training and skills-building workshops in information and communication technology that would benefit more than 3,000 public school teachers, for which she was accorded by Foothill College, the honor of naming after her the said international program, R.A.C.E. or Rachel Arenas Collaborative for Excellence. == Chairperson of the MTRCB ==