Junior Middleweight World/Lineal Champions (154lbs)

Sandro Mazzinghi (17/9/1964 - 18/6/1965)

Mazzinghi recognised by both the WBC and WBA as champion

Nino Benvenuti (18/6/1965 - 25/6/1966)

Ki-Soo Kim (25/6/1966 - 26/5/1968)

Sandro Mazzinghi (26/5/1968 - 30/11/1968)

Mazzinghi moved up in weight

Freddie Little (17/3/1969 - 9/7/1970)

Carmelo Bossi (9/7/1970 - 31/10/1971)

Koichi Wajima (31/10/1971 - 4/6/1974)
Oscar Albarado (4/6/1974 – 21/1/1975) 

Koichi Wajima (21/1/1975 – 7/6/1975)
Jae-Doo Yuh (7/6/1975 – 17/2/1976)
Koichi Wajima (17/2/1976 – 18/5/1976)
Jose Manuel Duran (18/5/1976 – 8/10/1976)
Miguel Castellini (8/10/1976 – 5/3/1977)
Eddie Gazo (5/3/1977 – 9/8/1978)
Masashi Kudo (9/8/1978 – 24/10/1979)
Ayub Kalule (24/10/1979 – 25/6/1981)
Sugar Ray Leonard (25/6/1981 – 22/9/1981)

Leonard moved down to welter
Thomas Hearns (3/12/1982 – 28/9/1986)

Hearns (2) beat Wilfred Benitez (1)
Hearns moved up in weight
Duane Thomas (5/12/1986 – 12/7/1987)

Thomas (4) beat John Mugabi (1)
Lupe Aquino (12/7/1987 – 2/10/1987)
Gianfranco Rosi (2/10/1987 – 8/7/1988)
Donald Curry (8/7/1988 – 11/2/1989)
Rene Jacquot (11/2/1989 – 8/7/1989) 
John Mugabi (8/7/1989 – 31/3/1990)
Terry Norris (31/3/1990 – 18/12/1993)
Simon Brown (18/12/1993 – 7/5/1994)
Terry Norris (7/5/1994 – 12/11/1994)
Luis Santana (12/11/1994 – 19/8/1995)
Terry Norris (19/8/1995 – 6/12/1997)
Keith Mullings (6/12/1997 – 29/1/1999)
Javier Castillejo (29/1/1999 – 23/6/2001)
Oscar De La Hoya (23/6/2001 – 13/9/2003)
Shane Mosley (13/9/2003 – 13/3/2004)
Ronald Wright (13/3/2004 – 25/4/2005)

Wright moved up in weight

Saul Alvarez (20/4/2013 – 14/9/2013)

Alvarez (2) beat Austin Trout (3) to become The Ring champion
Floyd Mayweather Jnr (14/9/2013 – 13/9/2015)
Mayweather retired​

Jarrett Hurd (7/4/2018 – 11/5/2019

Hurd (3) beat Erislandy Lara (1)

Julian Williams (11/5/2019 – 18/1/2020)

Jeison Rosario (18/1/2020 -

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