Thousands of mourners packed Riverside Church on Wednesday to remember Héctor Figueroa, the firebrand labor leader who gave a voice to the voiceless – the more than 175,000 service workers he represented.

The former president of SEIU Local 32BJ was remembered as a selfless fighter whose life was devoted to the labor movement and whose leadership transformed the union into a political force.

“The city became a better place from the moment Héctor became a leader here, from the moment we felt his passion, his belief,” Mayor Bill de Blasio said during a 12-minute eulogy. “There was something wonderfully youthful in the hope that ran through all he said.”

Figueroa, 57, died July 11 of a heart attack.

Also in attendance were New Jersey Gov. Phil Murphy and New York Attorney General Letitia James – although not Gov. Andrew Cuomo – and the thousands of union members who Figueroa championed.

“I’ve been in the military and if you know anybody who’s been in the military you follow some leaders into battle and some you’re reluctant to go,” union member Eric Thompson, a building superintendent from Mount Kisco, said outside the church.

“With Héctor any kind of labor movement I would follow him even if I may not agree with it because I trust his judgment,” he said. “Héctor is a modern-day Martin Luther King.”

Figueroa was known as an outspoken and unbending labor leader, fighting for his union members regardless of opposition or obstacles – as with his controversial support for a new Amazon headquarters in Long Island City, a plan he felt would benefit 32BJ but strongly opposed by other labor unions.

He also presided over an unprecedented growth in the union, both in political clout and membership, which grew to more than 175,000 on his watch. The membership is scattered across a dozen states, including more than 70,000 in its New York Metro District.

“Héctor followed his own drumbeat, in his eyes we were all playing on the same team, working to create a win-win situation for everyone,” said Eric Rudin, president of Rudin Management Company, who negotiated two contracts with Figueroa in recent years.

“He was gracious and soft-spoken. He was self-effacing and charming and he had an excellent sense of humor.”

Born in Ponce, Puerto Rico, to a pair of teachers who joined a local fight for labor rights, Figueroa would literally grow into the movement. At 24 he served as organizing director for the Service Employees International Union and helped win his parents’ the workers’ rights they long sought.

Figueroa left the island in 1982 and moved to the mainland, moving in with an aunt and uncle in the Bronx where he completed his education on a grant to study economics.

He plunged back into the labor movement in the garment industry, joining the Amalgamated Clothing and Textile Workers Union in 1990 and joining other labor leaders in lobbying against NAFTA.

He went on to join SEIU’s Janitors for Justice campaign, where he began his climb to the top of the union ladder – first as a deputy trustee, then secretary-treasurer, and finally as president in 2012.

Figueroa pushed the union into stronger political advocacy, pushing for immigrant rights and workplace safety.

32BJ lobbied strongly for the new minimum wage and the 2017 Fast Food Worker Empowerment Act, which provided benefits for fast food workers and allowed them to organize.

“He would have insisted that we carry on the struggle,” de Blasio said Friday. “He expressed this amazing optimism, this sense that we could do it no matter what the odds.”

Kyle Bragg, 60, who rose through the union ranks with Figueroa, was selected to replace him.

Figueroa is survived by his wife, Deidre, and two children.