
<PAGE>   1
 
                                                                    EXHIBIT 12.1
 
                            AMB PROPERTY CORPORATION
   COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES AND PREFERRED DIVIDENDS
                         (IN THOUSANDS, EXCEPT RATIOS)
<TABLE>
<CAPTION>
                                         FOR THE YEARS ENDED DECEMBER 31,        
                                  -----------------------------------------------
                                                                        1997     
                                  1993    1994     1995     1996    HISTORICAL(1)
                                  ----   ------   ------   ------   -------------
<S>                               <C>    <C>      <C>      <C>      <C>          
Earnings:
  Income (loss) from operations
    before minority interests...  $798   $2,925   $3,296   $7,140      $18,885   
  Interest expense..............    --       --        4       --        3,528   
                                  ----   ------   ------   ------      -------   
        Total earnings..........  $798   $2,925   $3,300   $7,140      $22,413   
                                  ====   ======   ======   ======      =======   
Fixed charges:
  Interest expense(4)...........  $ --   $   --   $    4   $   --      $ 3,528   
  Capitalized interest(5).......    --       --       --       --          448   
                                  ----   ------   ------   ------      -------   
        Total fixed charges.....  $ --   $   --   $    4   $   --      $ 3,976   
                                  ====   ======   ======   ======      =======   

Ratio of earnings to fixed
  charges.......................   N/A      N/A      825x     N/A          5.6x  
                                  ====   ======   ======   ======      =======   

<CAPTION>                                                
                                FOR THE NINE MONTHS ENDED
                                      SEPTEMBER 30,     
                                -------------------------
                                     1997         1998   
                                  HISTORICAL   HISTORICAL
                                  ----------   ----------
<S>                               <C>          <C>       
Earnings:
  Income (loss) from operations
    before minority interests...    $8,982     $ 91,372  
  Interest expense..............        --       47,105  
                                    ------     --------  
        Total earnings..........    $8,982     $138,477  
                                    ======     ========  
Fixed charges:
  Interest expense(2)...........    $   --     $ 47,105  
  Capitalized interest(3).......        --        4,974  
                                    ------     --------  
        Total fixed charges.....    $   --     $ 52,079  
                                    ======     ========  
Preferred Stock dividends.......        --        1,514  
                                    ------     --------  
        Total fixed charges and
          preferred dividends...    $   --     $ 53,593  
                                    ======     ========  
Ratio of earnings to fixed
  charges.......................       N/A          2.7x 
                                    ======     ========  
Ratio of earnings to fixed
  charges and preferred 
  dividends.....................       N/A          2.6x 
                                    ======     ========  
</TABLE>
 
---------------
(1) Historical ratio of earnings to fixed charges includes the results of the
    Predecessor for the period from January 1, 1997 through November 25, 1997,
    and the results of the Company subsequent to November 25, 1997, the date of
    acquisition by the Company.
 
(2) Includes amortization of debt premiums and deferred financing fees.
 
(3) Historical capitalized interest represents construction interest incurred
    subsequent to November 25, 1997, the date of acquisition by the Company.
