Ohio State has claimed six consensus national championships (four were pre BCS - AP wire service national titles) in 1944, 1954, 1957, 1968, in 2002 when the Buckeyes won the title in the BCS Championship Game defeating then #1 Miami in double overtine in the Fiesta Bowl and in the first College Football Playoff defeating Oregaon 42-20/

The NCAA did not conduct a national championship in Division I-A football and was not involved in the selection process. That changed in 2014. (Since 1998 through 2013, the Bowl Championship Series (BCS) has matched it's two top-ranked teams to determine a national champion. (Here is a LINK to the official BCS website.)

However, a number of polling organizations provide a final ranking of Division I-A football teams at the end of each season. Below are the years the Buckeyes were named national champions as determined by these polling organizations, including and in addition to the aforementioned five years cited.
 

2014 Consensus; won 1st CFB Playoff 2002 Ohio State: AP, BCS, Berryman, Billingsley, Colley, DeVold, Eck, FACT, FB News, FW, Massey, NFF, NY Times, Seattle Times, Sporting News, USA/ESPN, Wolfe 1975 Ohio St.: Berryman, FACT*, Helms*, Matthews*, Poling (Oklahoma) 1974 Ohio St.: Matthews 1973 Ohio St.: FACT, National Championship Foundation*, Poling* (Michigan) 1970 Ohio St.: NFF* (Texas) 1969 Ohio St.: Matthews 1968 Ohio St.: AP, Berryman, Billingsley, Dunkel, FACT, FB News, Football Research, FW, Helms, National Championship Foundation, NFF, Poling, UPI 1961 Ohio St.: FW, Poling 1957 Ohio St.: Boand, DeVold, FW, INS, Litkenhous, UPI 1954 Ohio St.: AP, Berryman, Boand, DeVold, Football Research*, Helms*, INS, National Championship Foundation*, Poling, Sagarin, Williamson (UCLA) 1944 Ohio St.: National Championship Foundation* (Army) 1942 Ohio St.: AP, Billingsley, Boand, Dunkel, Football Research, National Championship Foundation 1933 Ohio St.: Dunkel   * Organization chose multiple schools; other school listed in ( ). Polling Organizations Information

1906   Ohio Athletic Conference Champions     1912   Ohio Athletic Conference Champions     1916   Big Ten Conference Champions     1917   Big Ten Conference Champions     1920   Big Ten Conference Champions     1935   Big Ten Conference Co-Champions     1939   Big Ten Conference Champions     1942   Big Ten Conference Champions     1944   Big Ten Conference Champions     1949   Big Ten Conference Co-Champions     1954   Big Ten Conference Champions     1955  Big Ten Conference Champions     1957   Big Ten Conference Champions     1961   Big Ten Conference Champions     1968   Big Ten Conference Champions     1969   Big Ten Conference Co-Champions     1970   Big Ten Conference Champions     1972   Big Ten Conference Co-Champions     1973   Big Ten Conference Co-Champions     1974   Big Ten Conference Co-Champions     1975   Big Ten Conference Champions     1976   Big Ten Conference Co-Champions     1977   Big Ten Conference Co-Champions     1979   Big Ten Conference Champions     1981   Big Ten Conference Co-Champions     1984   Big Ten Conference Champions     1986   Big Ten Conference Co-Champions     1993   Big Ten Conference Co-Champions     1996   Big Ten Conference Co-Champions     1998   Big Ten Conference Co-Champions     2002   Big Ten Conference Co-Champions     2005   Big Ten Conference Champions     2006   Big Ten Conference Co-Champions     2007   Big Ten Conference Champions     2008   Big Ten Conference Co-Champions     2009   Big Ten Conference Champions     2014   Big Ten Conference Champions     2017   Big Ten Conference Champions     2018   Big Ten Conference Champions     2019   Big Ten Conference Champions OSU was an independent until 1901, joined the Ohio Athletic Conference in 1902 and stayed in it until 1921, while simultaneously joining the Big Ten in 1913.