O'Malley will host two solo events in Trenton and Paterson and appear alongside Booker in Newark, according to O'Malley's spokeswoman.
The one-day visit in advance of New Jersey's Aug. 13 primary comes just days after O'Malley said he was in the process of laying the framework for a presidential campaign, should he decide to run. New Jersey Gov. Chris Christie, a Republican, is also considered a likely 2016 presidential contender.
The two governors have traded jabs at each other's principles and policies over the past few years, but O'Malley's trip this week is designed to boost support for the popular Newark mayor seeking to fill the seat of late U.S. Sen. Frank Lautenberg, who died in June.
O'Malley has frequently campaigned for candidates in other states since he became chairman of the Democratic Governor's Association in 2011, a post he held for two years before becoming the organization's finance chairman this year. Those campaign efforts typically focused on electing Democrats as governors, and O'Malley also served as a campaign surrogate for President Barack Obama's 2012 re-election.
The term-limited governor this year raised $500,000 through his federal political action committee O'Say Can You See, some of which was sent to candidates in the early primary states of New Hampshire and Iowa.