Eldin was appointed and served in both New York City Mayor Mike Bloomberg and Bill de Blasio’s administration as the Deputy Commissioner for Public Information for the NYC Department of Corrections (Rikers Island), one of the largest jail complexes in the country. A member of the Commissioner’s management team, Eldin managed media relations, messaging/speech writing for a workforce of over 10,000 and a daily inmate population nearing 12,000. 

Earlier in his career, Eldin cut his teeth in the heady world of Bronx politics as chief of staff and later Chief Aide/Communications Director for City Council Member then Bronx Borough President Adolfo Carrion Jr. Eldin and his team established public relations strategies to help direct media attention toward small businesses and other neighborhood attractions rarely covered in The Bronx, helping to establish beautification projects and initiatives to boost economic development by creating Bronx At Work, an aggressive campaign to attract companies from across the region, provided they were able to offer contracts to local businesses and make jobs available to the the nearly 1.5 million residents living in the County of the Bronx. This campaign’s success was noted by Crain’s New York Business.

Eldin was also a partner at a Manhattan public relations firm, and served as a press secretary for NYC Council and City Hall officials, where he helped manage media relations for council committees' hearings that drew significant media attention to some of the city’s most heated issues, including the so-called Central Park Five incident.