NEWARK—For years, this city has watched nearby Hoboken and Jersey City be transformed by luxury apartments, restaurants and an influx of young professionals while it struggled to overcome a legacy of poverty, violence and corruption.

Now developers say the future of what was once an industrial hub is finally under way, with half-a-dozen downtown residential developments having received financing, broken ground or been completed within the past year. The hope is that the projects will bring thousands of residents, a more vibrant...