He was born in Joplin, Missouri on June 21, 1930, and is the eldest of three children. His father H. Carl Meredith (1896—1963) worked as an accountant, and along with his wife, Mildred Elaine Kohane Meredith (1902—1996), provided their family with a middle-class lifestyle while living in Joplin. During high school, he was very active and successful in sports. He participated in football, became a Missouri high school track champion in the 1-mile run, and was a Golden Gloves boxing champion. He and his family were also active members of the local Methodist church.

However, when he was a junior in high school , along with the encouragement of his uncle, Dr. C. Paul Meredith (1902—1968, a doctor of veterinary medicine for the state of Missouri), he began listening to Armstrong's The World Tomorrow radio program on station XEG. He also began receiving the Church's main monthly publication The Plain Truth magazine, along with numerous other literature the Church had offered free of charge.

In the autumn of 1949, following one year of attending Joplin Junior College (now called Missouri Southern State University), his growing religious convictions to Armstrong's teachings led him to enroll as a full time student at Armstrong's Church-founded Ambassador College in Pasadena, California. He became one of the liberal art institute's earliest students (Armstrong had founded the college just two years earlier), and was the student body class president during his senior year.

Over the next 43 years, he would become one of the leading executives and most influential ministers and writers within the top levels of the Church. He would in later years have repeated confrontations with colleagues over who should be in authority, always maintaining that he (Meredith) should be the one in charge.

Following his graduation in June 1952, Meredith was assigned by Armstrong to raise up and pastor churches in Portland, Oregon; San Diego, California; and Seattle and Tacoma, Washington. On December 20, 1952, after summoning him back to the Church's headquarters in Pasadena from his pastorship in Oregon, Armstrong ordained him and four other men - including his uncle Dr. C. Paul Meredith - to the high-ranking position of evangelist. These men were the very first evangelists of the WCG. Meredith was the youngest of the newly ordained men, and was the fifth to be ordained.

Over the following years, Meredith would help raise up scores of congregations throughout the United States. He would also conduct many baptizing and evangelizing tours in the United States, the United Kingdom, Europe, and Africa. From the early to mid-1950s, and again in 1960, he was assigned by Armstrong to live in Britain to start up congregations for the Church.

In addition to serving as a senior evangelist, Meredith held many high ranking and influential positions within the Worldwide Church of God. He was a member of the Council of Elders, a body of 12 evangelist-ranked men that assisted Armstrong in clarifying and establishing Church teachings. Throughout the 1960s, Meredith served as the 2nd Vice President of the Worldwide Church of God, which was the third highest position in the Church under Herbert Armstrong and his son Garner Ted Armstrong. He also served as 2nd Vice President of Ambassador College (late 1950s to early 1970s); Deputy Chancellor of Ambassador College at each of the school's three campuses in Pasadena, California (1972), Bricket Wood, England (1973), and Big Sandy, Texas (1986—1989). Meredith served briefly as the Dean of Faculty at Ambassador College in Pasadena (1978). Meredith served as a senior editor and associate editor of the church's flagship publication The Plain Truth magazine from 1953 to the early 1990s. He was also on the Church's Corporate Board of Directors from 1958-1973. He served periodically as a guest presenter on The World Tomorrow radio program in the mid-1950s, and acted as the Superintendent of the Church's ministry in the United States (this position was later renamed Director of Pastoral Administration) from 1961 to 1972, and for the Church's worldwide ministry from January to August 1979. He was the pastor of the Church's largest congregation, which was in Los Angeles, California, from 1964—1969, as well as the Senior Pastor of the Glendale, Bakersfield (he also pastored here in the early 1960s), and Reseda, California congregations from 1976 to 1978. In 1979, he pastored the high profile Pasadena Ambassador Auditorium congregation. In 1980, Armstrong sent Meredith to Hawaii on the basis of accusations made against Meredith. Armstrong also wrote a letter to Meredith which later found its way onto the internet. March 14, 1980 Letter to Roderick C. Meredith from Herbert Armstrong Note: this letter was apparently retyped from an old copy, a few places not being readable and marked with “[]”. Other corrections were made in brackets [ ]

On June 16, 1976, Meredith's wife of 20 years died. Margie Helen McNair was 40 years old when she died due to complications of cancer. She was also a sister of several prominent WCG evangelists. During their marriage, they had two sons, Michael Rea and James Paul, and two daughters, Elizabeth Helen and Rebecca Anne.

On November 20, 1977, he married his second wife, Sheryl Ann Hensley. They have two sons, David and Jonathan.

Meredith is a prolific writer who has written hundreds of articles and dozens of booklets since the early 1950s on topics ranging from Christian living, endtime prophecy, the plan of God, to mankind's ultimate future.

On Friday night, September 19, 2008 Meredith suffered a mild stroke. He was released from the hospital and was expected to recover.

Over the next several years following Armstrong's death on January 16, 1986, nearly all of the traditional teachings of the Church that had been established by Armstrong were drastically changed or completely discontinued by WCGs new leadership under Joseph W. Tkach. On December 10, 1992, Meredith was fired from the WCG ministry by Tkach for not agreeing to consent with these major - and in the eyes of the Armstrong tradionalists, heretical - doctrinal changes.

Several weeks later on December 26, 1992, he and 19 other members of the WCG who did not agree with the new direction the organization had undertaken, met for the commanded weekly seventh-day Sabbath service in the living room of his home. One week later on January 3, 1993, meeting in a small rented hall in Los Angeles, California, 42 people met for the first official Sabbath services of the newly incorporated Global Church of God (GCG), which Meredith had recently founded. The new organization's teachings and stated objectives closely mirrored that of Armstrong's original WCG.

By the Fall of 1993, the membership of the GCG had swelled to approximately 1,500. In June 1994, its corporate headquarters were relocated to San Diego, California.

Following a heated dispute with several members of the GCG's corporate Board of Directors over Meredith's (who also had been the only Chairman of the Board of the corporation since its inception five years earlier) leadership role and authority within the Church, he was subsequently fired by a 3-2 majority of the Board on November 25, 1998.

However, his firing was widely unpopular with most of the GCG membership, and approximately 80 percent left the organization and came with him. In addition to the majority of the membership coming with him, approximately 70 percent of GCG's ministers and Council of Elders joined with him as well.

Within days of his dismissal, he and others had founded a new organization, and named it the Living Church of God. It too was headquartered in San Diego. Ironically, the new headquarters was located in the same office building as the GCG board which had recently fired him. In early 2003, the Church's corporate headquarters was moved to Charlotte, North Carolina. In March 2005, an LCG congregation in Brookfield, Wisconsin was shot up by a gunman who some said was upset by Meredith's sermons about the end and demands for money. Meredith later stated the massacre brought his church a lot of unusual attention.

As of December 2009, the LCG had an active membership of approximately 8,100 people in over 290 churches and small groups in 40 countries, with over $11 million in revenue being received annually in the form of tithes, offerings, and gifts from its members, co-workers, and other supporters from around the world. Meredith is the organization's Chief Executive Officer as well as the Presiding Evangelist of the Church. He is also the Editor in Chief of its main print and internet publication, Tomorrow's World magazine. Meredith is one of the four regular presenters of the Church's nationally and internationally aired television program, Tomorrow's World. One of the program's presenters, evangelist Richard F. Ames, is married to Meredith's younger sister, Kathyrn.